diff --git a/pkgs/development/compilers/llvm/git/bintools/default.nix b/pkgs/development/compilers/llvm/git/bintools/default.nix
new file mode 100644
index 000000000000..53f7941e3369
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/bintools/default.nix
@@ -0,0 +1,29 @@
+{ runCommand, stdenv, llvm, lld, version }:
+
+let
+  prefix =
+    if stdenv.hostPlatform != stdenv.targetPlatform
+    then "${stdenv.targetPlatform.config}-"
+    else "";
+in runCommand "llvm-binutils-${version}" { preferLocalBuild = true; } ''
+   mkdir -p $out/bin
+   for prog in ${lld}/bin/*; do
+     ln -s $prog $out/bin/${prefix}$(basename $prog)
+   done
+   for prog in ${llvm}/bin/*; do
+     ln -sf $prog $out/bin/${prefix}$(basename $prog)
+   done
+
+   ln -s ${llvm}/bin/llvm-ar $out/bin/${prefix}ar
+   ln -s ${llvm}/bin/llvm-as $out/bin/${prefix}as
+   ln -s ${llvm}/bin/llvm-dwp $out/bin/${prefix}dwp
+   ln -s ${llvm}/bin/llvm-nm $out/bin/${prefix}nm
+   ln -s ${llvm}/bin/llvm-objcopy $out/bin/${prefix}objcopy
+   ln -s ${llvm}/bin/llvm-objdump $out/bin/${prefix}objdump
+   ln -s ${llvm}/bin/llvm-ranlib $out/bin/${prefix}ranlib
+   ln -s ${llvm}/bin/llvm-readelf $out/bin/${prefix}readelf
+   ln -s ${llvm}/bin/llvm-size $out/bin/${prefix}size
+   ln -s ${llvm}/bin/llvm-strip $out/bin/${prefix}strip
+
+   ln -s ${lld}/bin/lld $out/bin/${prefix}ld
+''
diff --git a/pkgs/development/compilers/llvm/git/clang/default.nix b/pkgs/development/compilers/llvm/git/clang/default.nix
new file mode 100644
index 000000000000..cfafe43c3a5f
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/clang/default.nix
@@ -0,0 +1,123 @@
+{ lib, stdenv, llvm_meta, src, cmake, libxml2, libllvm, version, python3
+, buildLlvmTools
+, fixDarwinDylibNames
+, enableManpages ? false
+}:
+
+let
+  self = stdenv.mkDerivation ({
+    pname = "clang";
+    inherit version;
+
+    inherit src;
+    sourceRoot = "source/clang";
+
+    nativeBuildInputs = [ cmake python3 ]
+      ++ lib.optional enableManpages python3.pkgs.sphinx
+      ++ lib.optional stdenv.hostPlatform.isDarwin fixDarwinDylibNames;
+
+    buildInputs = [ libxml2 libllvm ];
+
+    cmakeFlags = [
+      "-DCMAKE_CXX_FLAGS=-std=c++14"
+      "-DCLANGD_BUILD_XPC=OFF"
+      "-DLLVM_CONFIG_PATH=${libllvm.dev}/bin/llvm-config${lib.optionalString (stdenv.hostPlatform != stdenv.buildPlatform) "-native"}"
+    ] ++ lib.optionals enableManpages [
+      "-DCLANG_INCLUDE_DOCS=ON"
+      "-DLLVM_ENABLE_SPHINX=ON"
+      "-DSPHINX_OUTPUT_MAN=ON"
+      "-DSPHINX_OUTPUT_HTML=OFF"
+      "-DSPHINX_WARNINGS_AS_ERRORS=OFF"
+    ] ++ lib.optionals (stdenv.hostPlatform != stdenv.buildPlatform) [
+      "-DLLVM_TABLEGEN_EXE=${buildLlvmTools.llvm}/bin/llvm-tblgen"
+      "-DCLANG_TABLEGEN=${buildLlvmTools.libclang.dev}/bin/clang-tblgen"
+    ];
+
+    patches = [
+      ./purity.patch
+      # https://reviews.llvm.org/D51899
+      ./gnu-install-dirs.patch
+    ];
+
+    postPatch = ''
+      sed -i -e 's/DriverArgs.hasArg(options::OPT_nostdlibinc)/true/' \
+             -e 's/Args.hasArg(options::OPT_nostdlibinc)/true/' \
+             lib/Driver/ToolChains/*.cpp
+
+      # Patch for standalone doc building
+      sed -i '1s,^,find_package(Sphinx REQUIRED)\n,' docs/CMakeLists.txt
+    '' + lib.optionalString stdenv.hostPlatform.isMusl ''
+      sed -i -e 's/lgcc_s/lgcc_eh/' lib/Driver/ToolChains/*.cpp
+    '';
+
+    outputs = [ "out" "lib" "dev" "python" ];
+
+    # Clang expects to find LLVMgold in its own prefix
+    postInstall = ''
+      if [ -e ${libllvm.lib}/lib/LLVMgold.so ]; then
+        ln -sv ${libllvm.lib}/lib/LLVMgold.so $lib/lib
+      fi
+
+      ln -sv $out/bin/clang $out/bin/cpp
+
+      # Move libclang to 'lib' output
+      moveToOutput "lib/libclang.*" "$lib"
+      moveToOutput "lib/libclang-cpp.*" "$lib"
+      substituteInPlace $out/lib/cmake/clang/ClangTargets-release.cmake \
+          --replace "\''${_IMPORT_PREFIX}/lib/libclang." "$lib/lib/libclang." \
+          --replace "\''${_IMPORT_PREFIX}/lib/libclang-cpp." "$lib/lib/libclang-cpp."
+
+      mkdir -p $python/bin $python/share/clang/
+      mv $out/bin/{git-clang-format,scan-view} $python/bin
+      if [ -e $out/bin/set-xcode-analyzer ]; then
+        mv $out/bin/set-xcode-analyzer $python/bin
+      fi
+      mv $out/share/clang/*.py $python/share/clang
+      rm $out/bin/c-index-test
+
+      mkdir -p $dev/bin
+      cp bin/clang-tblgen $dev/bin
+    '';
+
+    passthru = {
+      isClang = true;
+      inherit libllvm;
+    };
+
+    meta = llvm_meta // {
+      homepage = "https://clang.llvm.org/";
+      description = "A C language family frontend for LLVM";
+      longDescription = ''
+        The Clang project provides a language front-end and tooling
+        infrastructure for languages in the C language family (C, C++, Objective
+        C/C++, OpenCL, CUDA, and RenderScript) for the LLVM project.
+        It aims to deliver amazingly fast compiles, extremely useful error and
+        warning messages and to provide a platform for building great source
+        level tools. The Clang Static Analyzer and clang-tidy are tools that
+        automatically find bugs in your code, and are great examples of the sort
+        of tools that can be built using the Clang frontend as a library to
+        parse C/C++ code.
+      '';
+    };
+  } // lib.optionalAttrs enableManpages {
+    pname = "clang-manpages";
+
+    buildPhase = ''
+      make docs-clang-man
+    '';
+
+    installPhase = ''
+      mkdir -p $out/share/man/man1
+      # Manually install clang manpage
+      cp docs/man/*.1 $out/share/man/man1/
+    '';
+
+    outputs = [ "out" ];
+
+    doCheck = false;
+
+    meta = llvm_meta // {
+      description = "man page for Clang ${version}";
+    };
+  });
+in self
diff --git a/pkgs/development/compilers/llvm/git/clang/gnu-install-dirs.patch b/pkgs/development/compilers/llvm/git/clang/gnu-install-dirs.patch
new file mode 100644
index 000000000000..b834d386b4eb
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/clang/gnu-install-dirs.patch
@@ -0,0 +1,235 @@
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index 9e74014134a0..976e6a1757fd 100644
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -5,6 +5,8 @@ cmake_minimum_required(VERSION 3.13.4)
+ if( CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR )
+   project(Clang)
+ 
++  include(GNUInstallDirs)
++
+   set(CMAKE_CXX_STANDARD 14 CACHE STRING "C++ standard to conform to")
+   set(CMAKE_CXX_STANDARD_REQUIRED YES)
+   set(CMAKE_CXX_EXTENSIONS NO)
+@@ -416,7 +418,7 @@ include_directories(BEFORE
+ 
+ if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
+   install(DIRECTORY include/clang include/clang-c
+-    DESTINATION include
++    DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
+     COMPONENT clang-headers
+     FILES_MATCHING
+     PATTERN "*.def"
+@@ -425,7 +427,7 @@ if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
+     )
+ 
+   install(DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/include/clang
+-    DESTINATION include
++    DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
+     COMPONENT clang-headers
+     FILES_MATCHING
+     PATTERN "CMakeFiles" EXCLUDE
+@@ -445,7 +447,7 @@ if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
+ 
+   add_custom_target(bash-autocomplete DEPENDS utils/bash-autocomplete.sh)
+   install(PROGRAMS utils/bash-autocomplete.sh
+-          DESTINATION share/clang
++          DESTINATION ${CMAKE_INSTALL_DATADIR}/clang
+           COMPONENT bash-autocomplete)
+   if(NOT LLVM_ENABLE_IDE)
+     add_llvm_install_targets(install-bash-autocomplete
+diff --git a/cmake/modules/AddClang.cmake b/cmake/modules/AddClang.cmake
+index 704278a0e93b..d25c8d325c71 100644
+--- a/cmake/modules/AddClang.cmake
++++ b/cmake/modules/AddClang.cmake
+@@ -123,9 +123,9 @@ macro(add_clang_library name)
+         install(TARGETS ${lib}
+           COMPONENT ${lib}
+           ${export_to_clangtargets}
+-          LIBRARY DESTINATION lib${LLVM_LIBDIR_SUFFIX}
+-          ARCHIVE DESTINATION lib${LLVM_LIBDIR_SUFFIX}
+-          RUNTIME DESTINATION bin)
++          LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}
++          ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}
++          RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
+ 
+         if (NOT LLVM_ENABLE_IDE)
+           add_llvm_install_targets(install-${lib}
+@@ -170,7 +170,7 @@ macro(add_clang_tool name)
+ 
+     install(TARGETS ${name}
+       ${export_to_clangtargets}
+-      RUNTIME DESTINATION bin
++      RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
+       COMPONENT ${name})
+ 
+     if(NOT LLVM_ENABLE_IDE)
+@@ -185,7 +185,7 @@ endmacro()
+ macro(add_clang_symlink name dest)
+   add_llvm_tool_symlink(${name} ${dest} ALWAYS_GENERATE)
+   # Always generate install targets
+-  llvm_install_symlink(${name} ${dest} ALWAYS_GENERATE)
++  llvm_install_symlink(${name} ${dest} ${CMAKE_INSTALL_FULL_BINDIR} ALWAYS_GENERATE)
+ endmacro()
+ 
+ function(clang_target_link_libraries target type)
+diff --git a/lib/Headers/CMakeLists.txt b/lib/Headers/CMakeLists.txt
+index b2c0ce8dd4a0..19e5443d8c25 100644
+--- a/lib/Headers/CMakeLists.txt
++++ b/lib/Headers/CMakeLists.txt
+@@ -215,7 +215,7 @@ set_target_properties(clang-resource-headers PROPERTIES
+   FOLDER "Misc"
+   RUNTIME_OUTPUT_DIRECTORY "${output_dir}")
+ 
+-set(header_install_dir lib${LLVM_LIBDIR_SUFFIX}/clang/${CLANG_VERSION}/include)
++set(header_install_dir ${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}/clang/${CLANG_VERSION}/include)
+ 
+ install(
+   FILES ${files} ${generated_files}
+diff --git a/tools/c-index-test/CMakeLists.txt b/tools/c-index-test/CMakeLists.txt
+index ceef4b08637c..8efad5520ca4 100644
+--- a/tools/c-index-test/CMakeLists.txt
++++ b/tools/c-index-test/CMakeLists.txt
+@@ -54,7 +54,7 @@ if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
+     set_property(TARGET c-index-test APPEND PROPERTY INSTALL_RPATH
+        "@executable_path/../../lib")
+   else()
+-    set(INSTALL_DESTINATION bin)
++    set(INSTALL_DESTINATION ${CMAKE_INSTALL_BINDIR})
+   endif()
+ 
+   install(TARGETS c-index-test
+diff --git a/tools/clang-format/CMakeLists.txt b/tools/clang-format/CMakeLists.txt
+index 35ecdb11253c..d77d75de0094 100644
+--- a/tools/clang-format/CMakeLists.txt
++++ b/tools/clang-format/CMakeLists.txt
+@@ -21,20 +21,20 @@ if( LLVM_LIB_FUZZING_ENGINE OR LLVM_USE_SANITIZE_COVERAGE )
+ endif()
+ 
+ install(PROGRAMS clang-format-bbedit.applescript
+-  DESTINATION share/clang
++  DESTINATION ${CMAKE_INSTALL_DATADIR}/clang
+   COMPONENT clang-format)
+ install(PROGRAMS clang-format-diff.py
+-  DESTINATION share/clang
++  DESTINATION ${CMAKE_INSTALL_DATADIR}/clang
+   COMPONENT clang-format)
+ install(PROGRAMS clang-format-sublime.py
+-  DESTINATION share/clang
++  DESTINATION ${CMAKE_INSTALL_DATADIR}/clang
+   COMPONENT clang-format)
+ install(PROGRAMS clang-format.el
+-  DESTINATION share/clang
++  DESTINATION ${CMAKE_INSTALL_DATADIR}/clang
+   COMPONENT clang-format)
+ install(PROGRAMS clang-format.py
+-  DESTINATION share/clang
++  DESTINATION ${CMAKE_INSTALL_DATADIR}/clang
+   COMPONENT clang-format)
+ install(PROGRAMS git-clang-format
+-  DESTINATION bin
++  DESTINATION ${CMAKE_INSTALL_BINDIR}
+   COMPONENT clang-format)
+diff --git a/tools/clang-rename/CMakeLists.txt b/tools/clang-rename/CMakeLists.txt
+index cda8e29ec5b1..0134d8ccd70b 100644
+--- a/tools/clang-rename/CMakeLists.txt
++++ b/tools/clang-rename/CMakeLists.txt
+@@ -19,8 +19,8 @@ clang_target_link_libraries(clang-rename
+   )
+ 
+ install(PROGRAMS clang-rename.py
+-  DESTINATION share/clang
++  DESTINATION ${CMAKE_INSTALL_DATADIR}/clang
+   COMPONENT clang-rename)
+ install(PROGRAMS clang-rename.el
+-  DESTINATION share/clang
++  DESTINATION ${CMAKE_INSTALL_DATADIR}/clang
+   COMPONENT clang-rename)
+diff --git a/tools/libclang/CMakeLists.txt b/tools/libclang/CMakeLists.txt
+index 51ff2e7e1565..1ed5f8a079a1 100644
+--- a/tools/libclang/CMakeLists.txt
++++ b/tools/libclang/CMakeLists.txt
+@@ -166,7 +166,7 @@ endif()
+ if(INTERNAL_INSTALL_PREFIX)
+   set(LIBCLANG_HEADERS_INSTALL_DESTINATION "${INTERNAL_INSTALL_PREFIX}/include")
+ else()
+-  set(LIBCLANG_HEADERS_INSTALL_DESTINATION include)
++  set(LIBCLANG_HEADERS_INSTALL_DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
+ endif()
+ 
+ install(DIRECTORY ../../include/clang-c
+@@ -196,7 +196,7 @@ foreach(PythonVersion ${CLANG_PYTHON_BINDINGS_VERSIONS})
+           COMPONENT
+             libclang-python-bindings
+           DESTINATION
+-            "lib${LLVM_LIBDIR_SUFFIX}/python${PythonVersion}/site-packages")
++            "${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}/python${PythonVersion}/site-packages")
+ endforeach()
+ if(NOT LLVM_ENABLE_IDE)
+   add_custom_target(libclang-python-bindings)
+diff --git a/tools/scan-build/CMakeLists.txt b/tools/scan-build/CMakeLists.txt
+index ec0702d76f18..d25d982f51da 100644
+--- a/tools/scan-build/CMakeLists.txt
++++ b/tools/scan-build/CMakeLists.txt
+@@ -47,7 +47,7 @@ if(CLANG_INSTALL_SCANBUILD)
+                        DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/bin/${BinFile})
+     list(APPEND Depends ${CMAKE_BINARY_DIR}/bin/${BinFile})
+     install(PROGRAMS bin/${BinFile}
+-            DESTINATION bin
++            DESTINATION ${CMAKE_INSTALL_BINDIR}
+             COMPONENT scan-build)
+   endforeach()
+ 
+@@ -61,7 +61,7 @@ if(CLANG_INSTALL_SCANBUILD)
+                        DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/libexec/${LibexecFile})
+     list(APPEND Depends ${CMAKE_BINARY_DIR}/libexec/${LibexecFile})
+     install(PROGRAMS libexec/${LibexecFile}
+-            DESTINATION libexec
++            DESTINATION ${CMAKE_INSTALL_LIBEXECDIR}
+             COMPONENT scan-build)
+   endforeach()
+ 
+@@ -89,7 +89,7 @@ if(CLANG_INSTALL_SCANBUILD)
+                        DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/share/scan-build/${ShareFile})
+     list(APPEND Depends ${CMAKE_BINARY_DIR}/share/scan-build/${ShareFile})
+     install(FILES share/scan-build/${ShareFile}
+-            DESTINATION share/scan-build
++            DESTINATION ${CMAKE_INSTALL_DATADIR}/scan-build
+             COMPONENT scan-build)
+   endforeach()
+ 
+diff --git a/tools/scan-view/CMakeLists.txt b/tools/scan-view/CMakeLists.txt
+index dd3d33439299..fea19c12ce70 100644
+--- a/tools/scan-view/CMakeLists.txt
++++ b/tools/scan-view/CMakeLists.txt
+@@ -19,7 +19,7 @@ if(CLANG_INSTALL_SCANVIEW)
+                        DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/bin/${BinFile})
+     list(APPEND Depends ${CMAKE_BINARY_DIR}/bin/${BinFile})
+     install(PROGRAMS bin/${BinFile}
+-            DESTINATION bin
++            DESTINATION ${CMAKE_INSTALL_BINDIR}
+             COMPONENT scan-view)
+   endforeach()
+ 
+@@ -33,7 +33,7 @@ if(CLANG_INSTALL_SCANVIEW)
+                        DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/share/${ShareFile})
+     list(APPEND Depends ${CMAKE_BINARY_DIR}/share/scan-view/${ShareFile})
+     install(FILES share/${ShareFile}
+-            DESTINATION share/scan-view
++            DESTINATION ${CMAKE_INSTALL_DATADIR}/scan-view
+             COMPONENT scan-view)
+   endforeach()
+ 
+diff --git a/utils/hmaptool/CMakeLists.txt b/utils/hmaptool/CMakeLists.txt
+index 62f2de0cb15c..6aa66825b6ec 100644
+--- a/utils/hmaptool/CMakeLists.txt
++++ b/utils/hmaptool/CMakeLists.txt
+@@ -10,7 +10,7 @@ add_custom_command(OUTPUT ${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR}/bin/${CLANG_HM
+ 
+ list(APPEND Depends ${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR}/bin/${CLANG_HMAPTOOL})
+ install(PROGRAMS ${CLANG_HMAPTOOL}
+-        DESTINATION bin
++        DESTINATION ${CMAKE_INSTALL_BINDIR}
+         COMPONENT hmaptool)
+ 
+ add_custom_target(hmaptool ALL DEPENDS ${Depends})
diff --git a/pkgs/development/compilers/llvm/git/clang/purity.patch b/pkgs/development/compilers/llvm/git/clang/purity.patch
new file mode 100644
index 000000000000..deb230a36c5b
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/clang/purity.patch
@@ -0,0 +1,28 @@
+From 4add81bba40dcec62c4ea4481be8e35ac53e89d8 Mon Sep 17 00:00:00 2001
+From: Will Dietz <w@wdtz.org>
+Date: Thu, 18 May 2017 11:56:12 -0500
+Subject: [PATCH] "purity" patch for 5.0
+
+---
+ lib/Driver/ToolChains/Gnu.cpp | 7 -------
+ 1 file changed, 7 deletions(-)
+
+diff --git a/lib/Driver/ToolChains/Gnu.cpp b/lib/Driver/ToolChains/Gnu.cpp
+index fe3c0191bb..c6a482bece 100644
+--- a/lib/Driver/ToolChains/Gnu.cpp
++++ b/lib/Driver/ToolChains/Gnu.cpp
+@@ -487,12 +487,6 @@ void tools::gnutools::Linker::ConstructJob(Compilation &C, const JobAction &JA,
+   if (!IsStatic) {
+     if (Args.hasArg(options::OPT_rdynamic))
+       CmdArgs.push_back("-export-dynamic");
+-
+-    if (!Args.hasArg(options::OPT_shared) && !IsStaticPIE) {
+-      CmdArgs.push_back("-dynamic-linker");
+-      CmdArgs.push_back(Args.MakeArgString(Twine(D.DyldPrefix) +
+-                                           ToolChain.getDynamicLinker(Args)));
+-    }
+   }
+ 
+   CmdArgs.push_back("-o");
+-- 
+2.11.0
diff --git a/pkgs/development/compilers/llvm/git/compiler-rt/X86-support-extension.patch b/pkgs/development/compilers/llvm/git/compiler-rt/X86-support-extension.patch
new file mode 100644
index 000000000000..f6f9336ad5ad
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/compiler-rt/X86-support-extension.patch
@@ -0,0 +1,23 @@
+diff --git a/lib/builtins/CMakeLists.txt b/lib/builtins/CMakeLists.txt
+index 3a66dd9c3fb..7efc85d9f9f 100644
+--- a/lib/builtins/CMakeLists.txt
++++ b/lib/builtins/CMakeLists.txt
+@@ -301,6 +301,10 @@ if (NOT MSVC)
+     i386/umoddi3.S
+   )
+ 
++  set(i486_SOURCES ${i386_SOURCES})
++  set(i586_SOURCES ${i386_SOURCES})
++  set(i686_SOURCES ${i386_SOURCES})
++
+   if (WIN32)
+     set(i386_SOURCES
+       ${i386_SOURCES}
+@@ -608,6 +612,7 @@ else ()
+   endif()
+ 
+   foreach (arch ${BUILTIN_SUPPORTED_ARCH})
++      message("arch: ${arch}")
+     if (CAN_TARGET_${arch})
+       # For ARM archs, exclude any VFP builtins if VFP is not supported
+       if (${arch} MATCHES "^(arm|armhf|armv7|armv7s|armv7k|armv7m|armv7em)$")
diff --git a/pkgs/development/compilers/llvm/git/compiler-rt/armv7l.patch b/pkgs/development/compilers/llvm/git/compiler-rt/armv7l.patch
new file mode 100644
index 000000000000..120cfe6feb2a
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/compiler-rt/armv7l.patch
@@ -0,0 +1,32 @@
+diff -ur compiler-rt-10.0.0.src/cmake/builtin-config-ix.cmake compiler-rt-10.0.0.src-patched/cmake/builtin-config-ix.cmake
+--- compiler-rt-10.0.0.src/cmake/builtin-config-ix.cmake	2020-03-24 00:01:02.000000000 +0900
++++ compiler-rt-10.0.0.src-patched/cmake/builtin-config-ix.cmake	2020-05-10 03:42:00.883450706 +0900
+@@ -24,7 +24,7 @@
+ 
+ 
+ set(ARM64 aarch64)
+-set(ARM32 arm armhf armv6m armv7m armv7em armv7 armv7s armv7k)
++set(ARM32 arm armhf armv6m armv7m armv7em armv7 armv7s armv7k armv7l)
+ set(HEXAGON hexagon)
+ set(X86 i386)
+ set(X86_64 x86_64)
+diff -ur compiler-rt-10.0.0.src/lib/builtins/CMakeLists.txt compiler-rt-10.0.0.src-patched/lib/builtins/CMakeLists.txt
+--- compiler-rt-10.0.0.src/lib/builtins/CMakeLists.txt	2020-03-24 00:01:02.000000000 +0900
++++ compiler-rt-10.0.0.src-patched/lib/builtins/CMakeLists.txt	2020-05-10 03:44:49.468579650 +0900
+@@ -474,6 +474,7 @@
+ set(armv7_SOURCES ${arm_SOURCES})
+ set(armv7s_SOURCES ${arm_SOURCES})
+ set(armv7k_SOURCES ${arm_SOURCES})
++set(armv7l_SOURCES ${arm_SOURCES})
+ set(arm64_SOURCES ${aarch64_SOURCES})
+ 
+ # macho_embedded archs
+@@ -595,7 +596,7 @@
+   foreach (arch ${BUILTIN_SUPPORTED_ARCH})
+     if (CAN_TARGET_${arch})
+       # For ARM archs, exclude any VFP builtins if VFP is not supported
+-      if (${arch} MATCHES "^(arm|armhf|armv7|armv7s|armv7k|armv7m|armv7em)$")
++      if (${arch} MATCHES "^(arm|armhf|armv7|armv7s|armv7k|armv7l|armv7m|armv7em)$")
+         string(REPLACE ";" " " _TARGET_${arch}_CFLAGS "${TARGET_${arch}_CFLAGS}")
+         check_compile_definition(__VFP_FP__ "${CMAKE_C_FLAGS} ${_TARGET_${arch}_CFLAGS}" COMPILER_RT_HAS_${arch}_VFP)
+         if(NOT COMPILER_RT_HAS_${arch}_VFP)
diff --git a/pkgs/development/compilers/llvm/git/compiler-rt/codesign.patch b/pkgs/development/compilers/llvm/git/compiler-rt/codesign.patch
new file mode 100644
index 000000000000..3cc12b94b200
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/compiler-rt/codesign.patch
@@ -0,0 +1,33 @@
+From 3dec5f3475a26aeb4678627795c4b67c6b7b4785 Mon Sep 17 00:00:00 2001
+From: Will Dietz <w@wdtz.org>
+Date: Tue, 19 Sep 2017 13:13:06 -0500
+Subject: [PATCH] remove codesign use on Apple, disable ios sim testing that
+ needs it
+
+---
+ cmake/Modules/AddCompilerRT.cmake |  8 ------
+ test/asan/CMakeLists.txt          | 52 ---------------------------------------
+ test/tsan/CMakeLists.txt          | 47 -----------------------------------
+ 3 files changed, 107 deletions(-)
+
+diff --git a/cmake/Modules/AddCompilerRT.cmake b/cmake/Modules/AddCompilerRT.cmake
+index bc5fb9ff7..b64eb4246 100644
+--- a/cmake/Modules/AddCompilerRT.cmake
++++ b/cmake/Modules/AddCompilerRT.cmake
+@@ -210,14 +210,6 @@ function(add_compiler_rt_runtime name type)
+         set_target_properties(${libname} PROPERTIES IMPORT_PREFIX "")
+         set_target_properties(${libname} PROPERTIES IMPORT_SUFFIX ".lib")
+       endif()
+-      if(APPLE)
+-        # Ad-hoc sign the dylibs
+-        add_custom_command(TARGET ${libname}
+-          POST_BUILD  
+-          COMMAND codesign --sign - $<TARGET_FILE:${libname}>
+-          WORKING_DIRECTORY ${COMPILER_RT_LIBRARY_OUTPUT_DIR}
+-        )
+-      endif()
+     endif()
+     install(TARGETS ${libname}
+       ARCHIVE DESTINATION ${COMPILER_RT_LIBRARY_INSTALL_DIR}
+2.14.1
+
diff --git a/pkgs/development/compilers/llvm/git/compiler-rt/default.nix b/pkgs/development/compilers/llvm/git/compiler-rt/default.nix
new file mode 100644
index 000000000000..8aeaabb0cd33
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/compiler-rt/default.nix
@@ -0,0 +1,113 @@
+{ lib, stdenv, llvm_meta, version, src, cmake, python3, llvm, libcxxabi }:
+
+let
+
+  useLLVM = stdenv.hostPlatform.useLLVM or false;
+  bareMetal = stdenv.hostPlatform.parsed.kernel.name == "none";
+  haveLibc = stdenv.cc.libc != null;
+  inherit (stdenv.hostPlatform) isMusl;
+
+in
+
+stdenv.mkDerivation {
+  pname = "compiler-rt" + lib.optionalString (haveLibc) "-libc";
+  inherit version;
+
+  inherit src;
+  sourceRoot = "source/compiler-rt";
+
+  nativeBuildInputs = [ cmake python3 llvm.dev ];
+  buildInputs = lib.optional stdenv.hostPlatform.isDarwin libcxxabi;
+
+  NIX_CFLAGS_COMPILE = [
+    "-DSCUDO_DEFAULT_OPTIONS=DeleteSizeMismatch=0:DeallocationTypeMismatch=0"
+  ];
+
+  cmakeFlags = [
+    "-DCOMPILER_RT_DEFAULT_TARGET_ONLY=ON"
+    "-DCMAKE_C_COMPILER_TARGET=${stdenv.hostPlatform.config}"
+    "-DCMAKE_ASM_COMPILER_TARGET=${stdenv.hostPlatform.config}"
+  ] ++ lib.optionals (useLLVM || bareMetal || isMusl) [
+    "-DCOMPILER_RT_BUILD_SANITIZERS=OFF"
+    "-DCOMPILER_RT_BUILD_XRAY=OFF"
+    "-DCOMPILER_RT_BUILD_LIBFUZZER=OFF"
+    "-DCOMPILER_RT_BUILD_PROFILE=OFF"
+  ] ++ lib.optionals ((useLLVM || bareMetal) && !haveLibc) [
+    "-DCMAKE_C_COMPILER_WORKS=ON"
+    "-DCMAKE_CXX_COMPILER_WORKS=ON"
+    "-DCOMPILER_RT_BAREMETAL_BUILD=ON"
+    "-DCMAKE_SIZEOF_VOID_P=${toString (stdenv.hostPlatform.parsed.cpu.bits / 8)}"
+  ] ++ lib.optionals (useLLVM && !haveLibc) [
+    "-DCMAKE_C_FLAGS=-nodefaultlibs"
+  ] ++ lib.optionals (useLLVM) [
+    "-DCOMPILER_RT_BUILD_BUILTINS=ON"
+    #https://stackoverflow.com/questions/53633705/cmake-the-c-compiler-is-not-able-to-compile-a-simple-test-program
+    "-DCMAKE_TRY_COMPILE_TARGET_TYPE=STATIC_LIBRARY"
+  ] ++ lib.optionals (bareMetal) [
+    "-DCOMPILER_RT_OS_DIR=baremetal"
+  ] ++ lib.optionals (stdenv.hostPlatform.isDarwin) [
+    "-DDARWIN_macosx_OVERRIDE_SDK_VERSION=ON"
+    "-DDARWIN_osx_ARCHS=${stdenv.hostPlatform.darwinArch}"
+    "-DDARWIN_osx_BUILTIN_ARCHS=${stdenv.hostPlatform.darwinArch}"
+  ];
+
+  outputs = [ "out" "dev" ];
+
+  patches = [
+    ./codesign.patch # Revert compiler-rt commit that makes codesign mandatory
+    ./X86-support-extension.patch # Add support for i486 i586 i686 by reusing i386 config
+    ./gnu-install-dirs.patch
+    # ld-wrapper dislikes `-rpath-link //nix/store`, so we normalize away the
+    # extra `/`.
+    ./normalize-var.patch
+  ]# ++ lib.optional stdenv.hostPlatform.isMusl ./sanitizers-nongnu.patch
+    ++ lib.optional stdenv.hostPlatform.isAarch32 ./armv7l.patch;
+
+  # TSAN requires XPC on Darwin, which we have no public/free source files for. We can depend on the Apple frameworks
+  # to get it, but they're unfree. Since LLVM is rather central to the stdenv, we patch out TSAN support so that Hydra
+  # can build this. If we didn't do it, basically the entire nixpkgs on Darwin would have an unfree dependency and we'd
+  # get no binary cache for the entire platform. If you really find yourself wanting the TSAN, make this controllable by
+  # a flag and turn the flag off during the stdenv build.
+  postPatch = lib.optionalString (!stdenv.isDarwin) ''
+    substituteInPlace cmake/builtin-config-ix.cmake \
+      --replace 'set(X86 i386)' 'set(X86 i386 i486 i586 i686)'
+  '' + lib.optionalString stdenv.isDarwin ''
+    substituteInPlace cmake/builtin-config-ix.cmake \
+      --replace 'set(ARM64 arm64 arm64e)' 'set(ARM64)'
+    substituteInPlace cmake/config-ix.cmake \
+      --replace 'set(COMPILER_RT_HAS_TSAN TRUE)' 'set(COMPILER_RT_HAS_TSAN FALSE)'
+  '' + lib.optionalString (useLLVM) ''
+    substituteInPlace lib/builtins/int_util.c \
+      --replace "#include <stdlib.h>" ""
+    substituteInPlace lib/builtins/clear_cache.c \
+      --replace "#include <assert.h>" ""
+    substituteInPlace lib/builtins/cpu_model.c \
+      --replace "#include <assert.h>" ""
+  '';
+
+  # Hack around weird upsream RPATH bug
+  postInstall = lib.optionalString (stdenv.hostPlatform.isDarwin || stdenv.hostPlatform.isWasm) ''
+    ln -s "$out/lib"/*/* "$out/lib"
+  '' + lib.optionalString (useLLVM) ''
+    ln -s $out/lib/*/clang_rt.crtbegin-*.o $out/lib/crtbegin.o
+    ln -s $out/lib/*/clang_rt.crtend-*.o $out/lib/crtend.o
+    ln -s $out/lib/*/clang_rt.crtbegin_shared-*.o $out/lib/crtbeginS.o
+    ln -s $out/lib/*/clang_rt.crtend_shared-*.o $out/lib/crtendS.o
+  '';
+
+  meta = llvm_meta // {
+    homepage = "https://compiler-rt.llvm.org/";
+    description = "Compiler runtime libraries";
+    longDescription = ''
+      The compiler-rt project provides highly tuned implementations of the
+      low-level code generator support routines like "__fixunsdfdi" and other
+      calls generated when a target doesn't have a short sequence of native
+      instructions to implement a core IR operation. It also provides
+      implementations of run-time libraries for dynamic testing tools such as
+      AddressSanitizer, ThreadSanitizer, MemorySanitizer, and DataFlowSanitizer.
+    '';
+    # "All of the code in the compiler-rt project is dual licensed under the MIT
+    # license and the UIUC License (a BSD-like license)":
+    license = with lib.licenses; [ mit ncsa ];
+  };
+}
diff --git a/pkgs/development/compilers/llvm/git/compiler-rt/gnu-install-dirs.patch b/pkgs/development/compilers/llvm/git/compiler-rt/gnu-install-dirs.patch
new file mode 100644
index 000000000000..5f025764de1c
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/compiler-rt/gnu-install-dirs.patch
@@ -0,0 +1,129 @@
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index b44ad2c2118e..d42f5664d448 100644
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -8,6 +8,7 @@ cmake_minimum_required(VERSION 3.13.4)
+ # Check if compiler-rt is built as a standalone project.
+ if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR OR COMPILER_RT_STANDALONE_BUILD)
+   project(CompilerRT C CXX ASM)
++  include(GNUInstallDirs)
+   set(COMPILER_RT_STANDALONE_BUILD TRUE)
+   set_property(GLOBAL PROPERTY USE_FOLDERS ON)
+ endif()
+diff --git a/cmake/Modules/AddCompilerRT.cmake b/cmake/Modules/AddCompilerRT.cmake
+index 361538a58e47..f0d8d9ab80f1 100644
+--- a/cmake/Modules/AddCompilerRT.cmake
++++ b/cmake/Modules/AddCompilerRT.cmake
+@@ -495,7 +495,7 @@ macro(add_compiler_rt_resource_file target_name file_name component)
+   add_custom_target(${target_name} DEPENDS ${dst_file})
+   # Install in Clang resource directory.
+   install(FILES ${file_name}
+-    DESTINATION ${COMPILER_RT_INSTALL_PATH}/share
++    DESTINATION ${COMPILER_RT_INSTALL_PATH}/${CMAKE_INSTALL_FULL_DATADIR}
+     COMPONENT ${component})
+   add_dependencies(${component} ${target_name})
+ 
+@@ -512,7 +512,7 @@ macro(add_compiler_rt_script name)
+   add_custom_target(${name} DEPENDS ${dst})
+   install(FILES ${dst}
+     PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE
+-    DESTINATION ${COMPILER_RT_INSTALL_PATH}/bin)
++    DESTINATION ${COMPILER_RT_INSTALL_PATH}/${CMAKE_INSTALL_FULL_BINDIR})
+ endmacro(add_compiler_rt_script src name)
+ 
+ # Builds custom version of libc++ and installs it in <prefix>.
+diff --git a/cmake/Modules/CompilerRTDarwinUtils.cmake b/cmake/Modules/CompilerRTDarwinUtils.cmake
+index 456a8dcda59f..7a09e74c7c79 100644
+--- a/cmake/Modules/CompilerRTDarwinUtils.cmake
++++ b/cmake/Modules/CompilerRTDarwinUtils.cmake
+@@ -508,7 +508,7 @@ macro(darwin_add_embedded_builtin_libraries)
+     set(DARWIN_macho_embedded_LIBRARY_OUTPUT_DIR
+       ${COMPILER_RT_OUTPUT_DIR}/lib/macho_embedded)
+     set(DARWIN_macho_embedded_LIBRARY_INSTALL_DIR
+-      ${COMPILER_RT_INSTALL_PATH}/lib/macho_embedded)
++      ${COMPILER_RT_INSTALL_PATH}/${CMAKE_INSTALL_FULL_LIBDIR}/macho_embedded)
+       
+     set(CFLAGS_armv7 "-target thumbv7-apple-darwin-eabi")
+     set(CFLAGS_i386 "-march=pentium")
+diff --git a/cmake/Modules/CompilerRTUtils.cmake b/cmake/Modules/CompilerRTUtils.cmake
+index f61d487e93a0..f1f46fb9599c 100644
+--- a/cmake/Modules/CompilerRTUtils.cmake
++++ b/cmake/Modules/CompilerRTUtils.cmake
+@@ -378,7 +378,7 @@ endfunction()
+ function(get_compiler_rt_install_dir arch install_dir)
+   if(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR AND NOT APPLE)
+     get_compiler_rt_target(${arch} target)
+-    set(${install_dir} ${COMPILER_RT_INSTALL_PATH}/lib/${target} PARENT_SCOPE)
++    set(${install_dir} ${COMPILER_RT_INSTALL_PATH}/${CMAKE_INSTALL_FULL_LIBDIR}/${target} PARENT_SCOPE)
+   else()
+     set(${install_dir} ${COMPILER_RT_LIBRARY_INSTALL_DIR} PARENT_SCOPE)
+   endif()
+diff --git a/cmake/base-config-ix.cmake b/cmake/base-config-ix.cmake
+index 1edab43e7c0d..1aac6b73ff82 100644
+--- a/cmake/base-config-ix.cmake
++++ b/cmake/base-config-ix.cmake
+@@ -65,11 +65,11 @@ if (LLVM_TREE_AVAILABLE)
+ else()
+     # Take output dir and install path from the user.
+   set(COMPILER_RT_OUTPUT_DIR ${CMAKE_CURRENT_BINARY_DIR} CACHE PATH
+-    "Path where built compiler-rt libraries should be stored.")
++    "Path where built compiler-rt build artifacts should be stored.")
+   set(COMPILER_RT_EXEC_OUTPUT_DIR ${CMAKE_CURRENT_BINARY_DIR}/bin CACHE PATH
+     "Path where built compiler-rt executables should be stored.")
+-  set(COMPILER_RT_INSTALL_PATH ${CMAKE_INSTALL_PREFIX} CACHE PATH
+-    "Path where built compiler-rt libraries should be installed.")
++  set(COMPILER_RT_INSTALL_PATH "" CACHE PATH
++    "Prefix where built compiler-rt artifacts should be installed, comes before CMAKE_INSTALL_PREFIX.")
+   option(COMPILER_RT_INCLUDE_TESTS "Generate and build compiler-rt unit tests." OFF)
+   option(COMPILER_RT_ENABLE_WERROR "Fail and stop if warning is triggered" OFF)
+   # Use a host compiler to compile/link tests.
+@@ -97,7 +97,7 @@ else(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR)
+   set(COMPILER_RT_LIBRARY_OUTPUT_DIR
+     ${COMPILER_RT_OUTPUT_DIR}/lib/${COMPILER_RT_OS_DIR})
+   set(COMPILER_RT_LIBRARY_INSTALL_DIR
+-    ${COMPILER_RT_INSTALL_PATH}/lib/${COMPILER_RT_OS_DIR})
++    ${COMPILER_RT_INSTALL_PATH}/${CMAKE_INSTALL_FULL_LIBDIR}/${COMPILER_RT_OS_DIR})
+ endif()
+ 
+ if(APPLE)
+diff --git a/include/CMakeLists.txt b/include/CMakeLists.txt
+index b00e8caa1ddd..0fe64e4862c9 100644
+--- a/include/CMakeLists.txt
++++ b/include/CMakeLists.txt
+@@ -69,22 +69,22 @@ set_target_properties(compiler-rt-headers PROPERTIES FOLDER "Compiler-RT Misc")
+ install(FILES ${SANITIZER_HEADERS}
+   COMPONENT compiler-rt-headers
+   PERMISSIONS OWNER_READ OWNER_WRITE GROUP_READ WORLD_READ
+-  DESTINATION ${COMPILER_RT_INSTALL_PATH}/include/sanitizer)
++  DESTINATION ${COMPILER_RT_INSTALL_PATH}/${CMAKE_INSTALL_FULL_INCLUDEDIR}/sanitizer)
+ # Install fuzzer headers.
+ install(FILES ${FUZZER_HEADERS}
+   COMPONENT compiler-rt-headers
+   PERMISSIONS OWNER_READ OWNER_WRITE GROUP_READ WORLD_READ
+-  DESTINATION ${COMPILER_RT_INSTALL_PATH}/include/fuzzer)
++  DESTINATION ${COMPILER_RT_INSTALL_PATH}/${CMAKE_INSTALL_FULL_INCLUDEDIR}/fuzzer)
+ # Install xray headers.
+ install(FILES ${XRAY_HEADERS}
+   COMPONENT compiler-rt-headers
+   PERMISSIONS OWNER_READ OWNER_WRITE GROUP_READ WORLD_READ
+-  DESTINATION ${COMPILER_RT_INSTALL_PATH}/include/xray)
++  DESTINATION ${COMPILER_RT_INSTALL_PATH}/${CMAKE_INSTALL_FULL_INCLUDEDIR}/xray)
+ # Install profile headers.
+ install(FILES ${PROFILE_HEADERS}
+   COMPONENT compiler-rt-headers
+   PERMISSIONS OWNER_READ OWNER_WRITE GROUP_READ WORLD_READ
+-  DESTINATION ${COMPILER_RT_INSTALL_PATH}/include/profile)
++  DESTINATION ${COMPILER_RT_INSTALL_PATH}/${CMAKE_INSTALL_FULL_INCLUDEDIR}/profile)
+ 
+ if (NOT CMAKE_CONFIGURATION_TYPES) # don't add this for IDEs.
+   add_custom_target(install-compiler-rt-headers
+diff --git a/lib/dfsan/CMakeLists.txt b/lib/dfsan/CMakeLists.txt
+index a29de8deff1b..d39ff01613d2 100644
+--- a/lib/dfsan/CMakeLists.txt
++++ b/lib/dfsan/CMakeLists.txt
+@@ -57,4 +57,4 @@ add_custom_command(OUTPUT ${dfsan_abilist_filename}
+                    DEPENDS done_abilist.txt libc_ubuntu1404_abilist.txt)
+ add_dependencies(dfsan dfsan_abilist)
+ install(FILES ${dfsan_abilist_filename}
+-        DESTINATION ${COMPILER_RT_INSTALL_PATH}/share)
++        DESTINATION ${COMPILER_RT_INSTALL_PATH}/${CMAKE_INSTALL_FULL_DATADIR})
diff --git a/pkgs/development/compilers/llvm/git/compiler-rt/normalize-var.patch b/pkgs/development/compilers/llvm/git/compiler-rt/normalize-var.patch
new file mode 100644
index 000000000000..135cf625ef78
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/compiler-rt/normalize-var.patch
@@ -0,0 +1,16 @@
+diff --git a/compiler-rt/cmake/Modules/CompilerRTUtils.cmake b/compiler-rt/cmake/Modules/CompilerRTUtils.cmake
+index f1f46fb9599c..6f19e69507ba 100644
+--- a/cmake/Modules/CompilerRTUtils.cmake
++++ b/cmake/Modules/CompilerRTUtils.cmake
+@@ -302,8 +302,9 @@ macro(load_llvm_config)
+     # Get some LLVM variables from LLVMConfig.
+     include("${LLVM_CMAKE_PATH}/LLVMConfig.cmake")
+ 
+-    set(LLVM_LIBRARY_OUTPUT_INTDIR
+-      ${LLVM_BINARY_DIR}/${CMAKE_CFG_INTDIR}/lib${LLVM_LIBDIR_SUFFIX})
++    get_filename_component(LLVM_LIBRARY_OUTPUT_INTDIR
++      ${LLVM_BINARY_DIR}/${CMAKE_CFG_INTDIR}/lib${LLVM_LIBDIR_SUFFIX}
++      REALPATH)
+   endif()
+ endmacro()
+ 
diff --git a/pkgs/development/compilers/llvm/git/compiler-rt/sanitizers-nongnu.patch b/pkgs/development/compilers/llvm/git/compiler-rt/sanitizers-nongnu.patch
new file mode 100644
index 000000000000..1f2ac97818eb
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/compiler-rt/sanitizers-nongnu.patch
@@ -0,0 +1,412 @@
+From f7a253f8f85d0f49df6b73996737a3e84ac64236 Mon Sep 17 00:00:00 2001
+From: Will Dietz <w@wdtz.org>
+Date: Mon, 24 Sep 2018 11:17:25 -0500
+Subject: [PATCH] Ported to 7.0, taken from gentoo-musl project.
+
+------
+Ported to compiler-rt-sanitizers-5.0.0. Taken from
+
+https://gist.githubusercontent.com/pwaller/2337f3290f12634cad3e3730cff0a6c1/raw/83c87a8585e2f9662494db5662e5361beb093c26/nongnu.patch
+Signed-off-by: Jory A. Pratt <anarchy@gentoo.org>
+
+Taken from gentoo-musl project, with a few additional minor fixes.
+---
+ lib/asan/asan_linux.cc                        |  4 +-
+ lib/interception/interception_linux.cc        |  2 +-
+ lib/interception/interception_linux.h         |  2 +-
+ lib/msan/msan_linux.cc                        |  2 +-
+ lib/sanitizer_common/sanitizer_allocator.cc   |  2 +-
+ .../sanitizer_common_interceptors_ioctl.inc   |  4 +-
+ .../sanitizer_common_syscalls.inc             |  2 +-
+ lib/sanitizer_common/sanitizer_linux.cc       |  8 +++-
+ .../sanitizer_linux_libcdep.cc                | 10 ++---
+ lib/sanitizer_common/sanitizer_platform.h     |  6 +++
+ .../sanitizer_platform_interceptors.h         |  4 +-
+ .../sanitizer_platform_limits_posix.cc        | 37 +++++++++++--------
+ lib/tsan/rtl/tsan_platform_linux.cc           |  2 +-
+ 13 files changed, 51 insertions(+), 34 deletions(-)
+
+diff --git a/lib/asan/asan_linux.cc b/lib/asan/asan_linux.cc
+index 625f32d40..73cf77aca 100644
+--- a/lib/asan/asan_linux.cc
++++ b/lib/asan/asan_linux.cc
+@@ -46,7 +46,7 @@
+ #include <link.h>
+ #endif
+ 
+-#if SANITIZER_ANDROID || SANITIZER_FREEBSD || SANITIZER_SOLARIS
++#if SANITIZER_ANDROID || SANITIZER_FREEBSD || SANITIZER_SOLARIS || SANITIZER_NONGNU
+ #include <ucontext.h>
+ extern "C" void* _DYNAMIC;
+ #elif SANITIZER_NETBSD
+@@ -139,7 +139,7 @@ void AsanApplyToGlobals(globals_op_fptr op, const void *needle) {
+   UNIMPLEMENTED();
+ }
+ 
+-#if SANITIZER_ANDROID
++#if SANITIZER_ANDROID || SANITIZER_NONGNU
+ // FIXME: should we do anything for Android?
+ void AsanCheckDynamicRTPrereqs() {}
+ void AsanCheckIncompatibleRT() {}
+diff --git a/lib/interception/interception_linux.cc b/lib/interception/interception_linux.cc
+index 26bfcd8f6..529b234f7 100644
+--- a/lib/interception/interception_linux.cc
++++ b/lib/interception/interception_linux.cc
+@@ -43,7 +43,7 @@ bool GetRealFunctionAddress(const char *func_name, uptr *func_addr,
+ }
+ 
+ // Android and Solaris do not have dlvsym
+-#if !SANITIZER_ANDROID && !SANITIZER_SOLARIS && !SANITIZER_OPENBSD
++#if !SANITIZER_ANDROID && !SANITIZER_SOLARIS && !SANITIZER_OPENBSD && !SANITIZER_NONGNU
+ void *GetFuncAddrVer(const char *func_name, const char *ver) {
+   return dlvsym(RTLD_NEXT, func_name, ver);
+ }
+diff --git a/lib/interception/interception_linux.h b/lib/interception/interception_linux.h
+index 942c25609..24a4d5080 100644
+--- a/lib/interception/interception_linux.h
++++ b/lib/interception/interception_linux.h
+@@ -36,7 +36,7 @@ void *GetFuncAddrVer(const char *func_name, const char *ver);
+       (::__interception::uptr) & WRAP(func))
+ 
+ // Android,  Solaris and OpenBSD do not have dlvsym
+-#if !SANITIZER_ANDROID && !SANITIZER_SOLARIS && !SANITIZER_OPENBSD
++#if !SANITIZER_ANDROID && !SANITIZER_SOLARIS && !SANITIZER_OPENBSD && !SANITIZER_NONGNU
+ #define INTERCEPT_FUNCTION_VER_LINUX_OR_FREEBSD(func, symver) \
+   (::__interception::real_##func = (func##_f)(                \
+        unsigned long)::__interception::GetFuncAddrVer(#func, symver))
+diff --git a/lib/msan/msan_linux.cc b/lib/msan/msan_linux.cc
+index 385a650c4..6e30a8ce9 100644
+--- a/lib/msan/msan_linux.cc
++++ b/lib/msan/msan_linux.cc
+@@ -13,7 +13,7 @@
+ //===----------------------------------------------------------------------===//
+ 
+ #include "sanitizer_common/sanitizer_platform.h"
+-#if SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD
++#if SANITIZER_FREEBSD || (SANITIZER_LINUX && !SANITIZER_NONGNU) || SANITIZER_NETBSD
+ 
+ #include "msan.h"
+ #include "msan_report.h"
+diff --git a/lib/sanitizer_common/sanitizer_allocator.cc b/lib/sanitizer_common/sanitizer_allocator.cc
+index 6bfd5e5ee..048f6154f 100644
+--- a/lib/sanitizer_common/sanitizer_allocator.cc
++++ b/lib/sanitizer_common/sanitizer_allocator.cc
+@@ -27,7 +27,7 @@ const char *SecondaryAllocatorName = "LargeMmapAllocator";
+ 
+ // ThreadSanitizer for Go uses libc malloc/free.
+ #if SANITIZER_GO || defined(SANITIZER_USE_MALLOC)
+-# if SANITIZER_LINUX && !SANITIZER_ANDROID
++# if SANITIZER_LINUX && !SANITIZER_ANDROID && !SANITIZER_NONGNU
+ extern "C" void *__libc_malloc(uptr size);
+ #  if !SANITIZER_GO
+ extern "C" void *__libc_memalign(uptr alignment, uptr size);
+diff --git a/lib/sanitizer_common/sanitizer_common_interceptors_ioctl.inc b/lib/sanitizer_common/sanitizer_common_interceptors_ioctl.inc
+index 2d633c173..b6eb23116 100644
+--- a/lib/sanitizer_common/sanitizer_common_interceptors_ioctl.inc
++++ b/lib/sanitizer_common/sanitizer_common_interceptors_ioctl.inc
+@@ -104,7 +104,7 @@ static void ioctl_table_fill() {
+   _(SIOCGETVIFCNT, WRITE, struct_sioc_vif_req_sz);
+ #endif
+ 
+-#if SANITIZER_LINUX
++#if SANITIZER_LINUX && !SANITIZER_NONGNU
+   // Conflicting request ids.
+   // _(CDROMAUDIOBUFSIZ, NONE, 0);
+   // _(SNDCTL_TMR_CONTINUE, NONE, 0);
+@@ -365,7 +365,7 @@ static void ioctl_table_fill() {
+   _(VT_WAITACTIVE, NONE, 0);
+ #endif
+ 
+-#if SANITIZER_LINUX && !SANITIZER_ANDROID
++#if SANITIZER_LINUX && !SANITIZER_ANDROID && !SANITIZER_NONGNU
+   // _(SIOCDEVPLIP, WRITE, struct_ifreq_sz); // the same as EQL_ENSLAVE
+   _(CYGETDEFTHRESH, WRITE, sizeof(int));
+   _(CYGETDEFTIMEOUT, WRITE, sizeof(int));
+diff --git a/lib/sanitizer_common/sanitizer_common_syscalls.inc b/lib/sanitizer_common/sanitizer_common_syscalls.inc
+index 469c8eb7e..24f87867d 100644
+--- a/lib/sanitizer_common/sanitizer_common_syscalls.inc
++++ b/lib/sanitizer_common/sanitizer_common_syscalls.inc
+@@ -2038,7 +2038,7 @@ POST_SYSCALL(setrlimit)(long res, long resource, void *rlim) {
+   }
+ }
+ 
+-#if !SANITIZER_ANDROID
++#if !SANITIZER_ANDROID && !SANITIZER_NONGNU
+ PRE_SYSCALL(prlimit64)(long pid, long resource, const void *new_rlim,
+                        void *old_rlim) {
+   if (new_rlim) PRE_READ(new_rlim, struct_rlimit64_sz);
+diff --git a/lib/sanitizer_common/sanitizer_linux.cc b/lib/sanitizer_common/sanitizer_linux.cc
+index 96d6c1eff..9e2b7fb9d 100644
+--- a/lib/sanitizer_common/sanitizer_linux.cc
++++ b/lib/sanitizer_common/sanitizer_linux.cc
+@@ -541,13 +541,13 @@ const char *GetEnv(const char *name) {
+ #endif
+ }
+ 
+-#if !SANITIZER_FREEBSD && !SANITIZER_NETBSD && !SANITIZER_OPENBSD
++#if !SANITIZER_FREEBSD && !SANITIZER_NETBSD && !SANITIZER_OPENBSD && !SANITIZER_NONGNU
+ extern "C" {
+ SANITIZER_WEAK_ATTRIBUTE extern void *__libc_stack_end;
+ }
+ #endif
+ 
+-#if !SANITIZER_GO && !SANITIZER_FREEBSD && !SANITIZER_NETBSD &&                \
++#if (!SANITIZER_GO || SANITIZER_NONGNU) && !SANITIZER_FREEBSD && !SANITIZER_NETBSD &&                \
+     !SANITIZER_OPENBSD
+ static void ReadNullSepFileToArray(const char *path, char ***arr,
+                                    int arr_size) {
+@@ -590,6 +590,10 @@ static void GetArgsAndEnv(char ***argv, char ***envp) {
+ #elif SANITIZER_NETBSD
+   *argv = __ps_strings->ps_argvstr;
+   *envp = __ps_strings->ps_envstr;
++#elif SANITIZER_NONGNU
++    static const int kMaxArgv = 2000, kMaxEnvp = 2000;
++    ReadNullSepFileToArray("/proc/self/cmdline", argv, kMaxArgv);
++    ReadNullSepFileToArray("/proc/self/environ", envp, kMaxEnvp);
+ #else // SANITIZER_FREEBSD
+ #if !SANITIZER_GO
+   if (&__libc_stack_end) {
+diff --git a/lib/sanitizer_common/sanitizer_linux_libcdep.cc b/lib/sanitizer_common/sanitizer_linux_libcdep.cc
+index 4962ff832..438f94dbe 100644
+--- a/lib/sanitizer_common/sanitizer_linux_libcdep.cc
++++ b/lib/sanitizer_common/sanitizer_linux_libcdep.cc
+@@ -179,7 +179,7 @@ __attribute__((unused)) static bool GetLibcVersion(int *major, int *minor,
+ }
+ 
+ #if !SANITIZER_FREEBSD && !SANITIZER_ANDROID && !SANITIZER_GO &&               \
+-    !SANITIZER_NETBSD && !SANITIZER_OPENBSD && !SANITIZER_SOLARIS
++    !SANITIZER_NETBSD && !SANITIZER_OPENBSD && !SANITIZER_SOLARIS && !SANITIZER_NONGNU
+ static uptr g_tls_size;
+ 
+ #ifdef __i386__
+@@ -261,7 +261,7 @@ void InitTlsSize() { }
+ #if (defined(__x86_64__) || defined(__i386__) || defined(__mips__) ||          \
+      defined(__aarch64__) || defined(__powerpc64__) || defined(__s390__) ||    \
+      defined(__arm__)) &&                                                      \
+-    SANITIZER_LINUX && !SANITIZER_ANDROID
++    SANITIZER_LINUX && !SANITIZER_ANDROID && !SANITIZER_NONGNU
+ // sizeof(struct pthread) from glibc.
+ static atomic_uintptr_t thread_descriptor_size;
+ 
+@@ -426,7 +426,7 @@ int GetSizeFromHdr(struct dl_phdr_info *info, size_t size, void *data) {
+ 
+ #if !SANITIZER_GO
+ static void GetTls(uptr *addr, uptr *size) {
+-#if SANITIZER_LINUX && !SANITIZER_ANDROID
++#if SANITIZER_LINUX && !SANITIZER_ANDROID && !SANITIZER_NONGNU
+ # if defined(__x86_64__) || defined(__i386__) || defined(__s390__)
+   *addr = ThreadSelf();
+   *size = GetTlsSize();
+@@ -470,7 +470,7 @@ static void GetTls(uptr *addr, uptr *size) {
+ #elif SANITIZER_OPENBSD
+   *addr = 0;
+   *size = 0;
+-#elif SANITIZER_ANDROID
++#elif SANITIZER_ANDROID || SANITIZER_NONGNU
+   *addr = 0;
+   *size = 0;
+ #elif SANITIZER_SOLARIS
+@@ -486,7 +486,7 @@ static void GetTls(uptr *addr, uptr *size) {
+ #if !SANITIZER_GO
+ uptr GetTlsSize() {
+ #if SANITIZER_FREEBSD || SANITIZER_ANDROID || SANITIZER_NETBSD ||              \
+-    SANITIZER_OPENBSD || SANITIZER_SOLARIS
++    SANITIZER_OPENBSD || SANITIZER_SOLARIS || SANITIZER_NONGNU
+   uptr addr, size;
+   GetTls(&addr, &size);
+   return size;
+diff --git a/lib/sanitizer_common/sanitizer_platform.h b/lib/sanitizer_common/sanitizer_platform.h
+index d81e25580..e10680ac8 100644
+--- a/lib/sanitizer_common/sanitizer_platform.h
++++ b/lib/sanitizer_common/sanitizer_platform.h
+@@ -208,6 +208,12 @@
+ # define SANITIZER_SOLARIS32 0
+ #endif
+ 
++#if defined(__linux__) && !defined(__GLIBC__)
++# define SANITIZER_NONGNU 1
++#else
++# define SANITIZER_NONGNU 0
++#endif
++
+ #if defined(__myriad2__)
+ # define SANITIZER_MYRIAD2 1
+ #else
+diff --git a/lib/sanitizer_common/sanitizer_platform_interceptors.h b/lib/sanitizer_common/sanitizer_platform_interceptors.h
+index f95539a73..6c53b3415 100644
+--- a/lib/sanitizer_common/sanitizer_platform_interceptors.h
++++ b/lib/sanitizer_common/sanitizer_platform_interceptors.h
+@@ -39,7 +39,7 @@
+ # include "sanitizer_platform_limits_solaris.h"
+ #endif
+ 
+-#if SANITIZER_LINUX && !SANITIZER_ANDROID
++#if SANITIZER_LINUX && !SANITIZER_ANDROID && !SANITIZER_NONGNU
+ # define SI_LINUX_NOT_ANDROID 1
+ #else
+ # define SI_LINUX_NOT_ANDROID 0
+@@ -322,7 +322,7 @@
+ #define SANITIZER_INTERCEPT_ETHER_R (SI_FREEBSD || SI_LINUX_NOT_ANDROID)
+ #define SANITIZER_INTERCEPT_SHMCTL          \
+   (SI_NETBSD || SI_OPENBSD || SI_SOLARIS || \
+-  ((SI_FREEBSD || SI_LINUX_NOT_ANDROID) && \
++  ((SI_FREEBSD || SI_LINUX_NOT_ANDROID || SANITIZER_NONGNU) && \
+     SANITIZER_WORDSIZE == 64))  // NOLINT
+ #define SANITIZER_INTERCEPT_RANDOM_R SI_LINUX_NOT_ANDROID
+ #define SANITIZER_INTERCEPT_PTHREAD_ATTR_GET SI_POSIX
+diff --git a/lib/sanitizer_common/sanitizer_platform_limits_posix.cc b/lib/sanitizer_common/sanitizer_platform_limits_posix.cc
+index 54da635d7..2f6ff69c3 100644
+--- a/lib/sanitizer_common/sanitizer_platform_limits_posix.cc
++++ b/lib/sanitizer_common/sanitizer_platform_limits_posix.cc
+@@ -14,6 +14,9 @@
+ 
+ #include "sanitizer_platform.h"
+ 
++// Workaround musl <--> linux conflicting definition of 'struct sysinfo'
++#define _LINUX_SYSINFO_H
++
+ #if SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_MAC
+ // Tests in this file assume that off_t-dependent data structures match the
+ // libc ABI. For example, struct dirent here is what readdir() function (as
+@@ -138,12 +141,14 @@ typedef struct user_fpregs elf_fpregset_t;
+ 
+ #if SANITIZER_LINUX && !SANITIZER_ANDROID
+ #include <glob.h>
+-#include <obstack.h>
++#  if !SANITIZER_NONGNU
++#    include <obstack.h>
++#  endif
+ #include <mqueue.h>
+-#include <net/if_ppp.h>
+-#include <netax25/ax25.h>
+-#include <netipx/ipx.h>
+-#include <netrom/netrom.h>
++#include <linux/if_ppp.h>
++#include <linux/ax25.h>
++#include <linux/ipx.h>
++#include <linux/netrom.h>
+ #if HAVE_RPC_XDR_H
+ # include <rpc/xdr.h>
+ #elif HAVE_TIRPC_RPC_XDR_H
+@@ -251,7 +256,7 @@ namespace __sanitizer {
+   unsigned struct_itimerspec_sz = sizeof(struct itimerspec);
+ #endif // SANITIZER_LINUX || SANITIZER_FREEBSD
+ 
+-#if SANITIZER_LINUX && !SANITIZER_ANDROID
++#if SANITIZER_LINUX && !SANITIZER_ANDROID && !SANITIZER_NONGNU
+   // Use pre-computed size of struct ustat to avoid <sys/ustat.h> which
+   // has been removed from glibc 2.28.
+ #if defined(__aarch64__) || defined(__s390x__) || defined (__mips64) \
+@@ -322,7 +327,7 @@ unsigned struct_ElfW_Phdr_sz = sizeof(ElfW(Phdr));
+ unsigned struct_ElfW_Phdr_sz = sizeof(Elf_Phdr);
+ #endif
+ 
+-#if (SANITIZER_LINUX || SANITIZER_FREEBSD) && !SANITIZER_ANDROID
++#if (SANITIZER_LINUX || SANITIZER_FREEBSD) && !SANITIZER_ANDROID && !SANITIZER_NONGNU
+   int glob_nomatch = GLOB_NOMATCH;
+   int glob_altdirfunc = GLOB_ALTDIRFUNC;
+ #endif
+@@ -416,7 +421,7 @@ unsigned struct_ElfW_Phdr_sz = sizeof(Elf_Phdr);
+   unsigned struct_termios_sz = sizeof(struct termios);
+   unsigned struct_winsize_sz = sizeof(struct winsize);
+ 
+-#if SANITIZER_LINUX
++#if SANITIZER_LINUX && !SANITIZER_NONGNU
+   unsigned struct_arpreq_sz = sizeof(struct arpreq);
+   unsigned struct_cdrom_msf_sz = sizeof(struct cdrom_msf);
+   unsigned struct_cdrom_multisession_sz = sizeof(struct cdrom_multisession);
+@@ -466,7 +471,7 @@ unsigned struct_ElfW_Phdr_sz = sizeof(Elf_Phdr);
+   unsigned struct_vt_mode_sz = sizeof(struct vt_mode);
+ #endif // SANITIZER_LINUX || SANITIZER_FREEBSD
+ 
+-#if SANITIZER_LINUX && !SANITIZER_ANDROID
++#if SANITIZER_LINUX && !SANITIZER_ANDROID && !SANITIZER_NONGNU
+   unsigned struct_ax25_parms_struct_sz = sizeof(struct ax25_parms_struct);
+   unsigned struct_cyclades_monitor_sz = sizeof(struct cyclades_monitor);
+ #if EV_VERSION > (0x010000)
+@@ -834,7 +839,7 @@ unsigned struct_ElfW_Phdr_sz = sizeof(Elf_Phdr);
+   unsigned IOCTL_VT_WAITACTIVE = VT_WAITACTIVE;
+ #endif // SANITIZER_LINUX || SANITIZER_FREEBSD
+ 
+-#if SANITIZER_LINUX && !SANITIZER_ANDROID
++#if SANITIZER_LINUX && !SANITIZER_ANDROID && !SANITIZER_NONGNU
+   unsigned IOCTL_CYGETDEFTHRESH = CYGETDEFTHRESH;
+   unsigned IOCTL_CYGETDEFTIMEOUT = CYGETDEFTIMEOUT;
+   unsigned IOCTL_CYGETMON = CYGETMON;
+@@ -989,7 +994,7 @@ CHECK_SIZE_AND_OFFSET(dl_phdr_info, dlpi_phdr);
+ CHECK_SIZE_AND_OFFSET(dl_phdr_info, dlpi_phnum);
+ #endif // SANITIZER_LINUX || SANITIZER_FREEBSD
+ 
+-#if (SANITIZER_LINUX || SANITIZER_FREEBSD) && !SANITIZER_ANDROID
++#if (SANITIZER_LINUX || SANITIZER_FREEBSD) && !SANITIZER_ANDROID && !SANITIZER_NONGNU
+ CHECK_TYPE_SIZE(glob_t);
+ CHECK_SIZE_AND_OFFSET(glob_t, gl_pathc);
+ CHECK_SIZE_AND_OFFSET(glob_t, gl_pathv);
+@@ -1023,6 +1028,7 @@ CHECK_TYPE_SIZE(iovec);
+ CHECK_SIZE_AND_OFFSET(iovec, iov_base);
+ CHECK_SIZE_AND_OFFSET(iovec, iov_len);
+ 
++#if !SANITIZER_NONGNU
+ CHECK_TYPE_SIZE(msghdr);
+ CHECK_SIZE_AND_OFFSET(msghdr, msg_name);
+ CHECK_SIZE_AND_OFFSET(msghdr, msg_namelen);
+@@ -1036,6 +1042,7 @@ CHECK_TYPE_SIZE(cmsghdr);
+ CHECK_SIZE_AND_OFFSET(cmsghdr, cmsg_len);
+ CHECK_SIZE_AND_OFFSET(cmsghdr, cmsg_level);
+ CHECK_SIZE_AND_OFFSET(cmsghdr, cmsg_type);
++#endif
+ 
+ #ifndef __GLIBC_PREREQ
+ #define __GLIBC_PREREQ(x, y) 0
+@@ -1145,7 +1152,7 @@ CHECK_SIZE_AND_OFFSET(mntent, mnt_passno);
+ 
+ CHECK_TYPE_SIZE(ether_addr);
+ 
+-#if (SANITIZER_LINUX || SANITIZER_FREEBSD) && !SANITIZER_ANDROID
++#if (SANITIZER_LINUX || SANITIZER_FREEBSD) && !SANITIZER_ANDROID && !SANITIZER_NONGNU
+ CHECK_TYPE_SIZE(ipc_perm);
+ # if SANITIZER_FREEBSD
+ CHECK_SIZE_AND_OFFSET(ipc_perm, key);
+@@ -1206,7 +1213,7 @@ CHECK_SIZE_AND_OFFSET(ifaddrs, ifa_dstaddr);
+ CHECK_SIZE_AND_OFFSET(ifaddrs, ifa_data);
+ #endif
+ 
+-#if SANITIZER_LINUX
++#if SANITIZER_LINUX && !SANITIZER_NONGNU
+ COMPILER_CHECK(sizeof(__sanitizer_mallinfo) == sizeof(struct mallinfo));
+ #endif
+ 
+@@ -1256,7 +1263,7 @@ COMPILER_CHECK(__sanitizer_XDR_DECODE == XDR_DECODE);
+ COMPILER_CHECK(__sanitizer_XDR_FREE == XDR_FREE);
+ #endif
+ 
+-#if SANITIZER_LINUX && !SANITIZER_ANDROID
++#if SANITIZER_LINUX && !SANITIZER_ANDROID && !SANITIZER_NONGNU
+ COMPILER_CHECK(sizeof(__sanitizer_FILE) <= sizeof(FILE));
+ CHECK_SIZE_AND_OFFSET(FILE, _flags);
+ CHECK_SIZE_AND_OFFSET(FILE, _IO_read_ptr);
+@@ -1275,7 +1282,7 @@ CHECK_SIZE_AND_OFFSET(FILE, _chain);
+ CHECK_SIZE_AND_OFFSET(FILE, _fileno);
+ #endif
+ 
+-#if SANITIZER_LINUX && !SANITIZER_ANDROID
++#if SANITIZER_LINUX && !SANITIZER_ANDROID && !SANITIZER_NONGNU
+ COMPILER_CHECK(sizeof(__sanitizer__obstack_chunk) <= sizeof(_obstack_chunk));
+ CHECK_SIZE_AND_OFFSET(_obstack_chunk, limit);
+ CHECK_SIZE_AND_OFFSET(_obstack_chunk, prev);
+diff --git a/lib/tsan/rtl/tsan_platform_linux.cc b/lib/tsan/rtl/tsan_platform_linux.cc
+index de989b780..51a97b554 100644
+--- a/lib/tsan/rtl/tsan_platform_linux.cc
++++ b/lib/tsan/rtl/tsan_platform_linux.cc
+@@ -294,7 +294,7 @@ void InitializePlatform() {
+ // This is required to properly "close" the fds, because we do not see internal
+ // closes within glibc. The code is a pure hack.
+ int ExtractResolvFDs(void *state, int *fds, int nfd) {
+-#if SANITIZER_LINUX && !SANITIZER_ANDROID
++#if SANITIZER_LINUX && !SANITIZER_ANDROID && !SANITIZER_NONGNU
+   int cnt = 0;
+   struct __res_state *statp = (struct __res_state*)state;
+   for (int i = 0; i < MAXNS && cnt < nfd; i++) {
+-- 
+2.19.0
+
diff --git a/pkgs/development/compilers/llvm/git/default.nix b/pkgs/development/compilers/llvm/git/default.nix
new file mode 100644
index 000000000000..eb068f6d4722
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/default.nix
@@ -0,0 +1,268 @@
+{ lowPrio, newScope, pkgs, lib, stdenv, cmake
+, gccForLibs, preLibcCrossHeaders
+, libxml2, python3, isl, fetchFromGitHub, overrideCC, wrapCCWith, wrapBintoolsWith
+, buildLlvmTools # tools, but from the previous stage, for cross
+, targetLlvmLibraries # libraries, but from the next stage, for cross
+# This is the default binutils, but with *this* version of LLD rather
+# than the default LLVM verion's, if LLD is the choice. We use these for
+# the `useLLVM` bootstrapping below.
+, bootBintoolsNoLibc ?
+    if stdenv.targetPlatform.linker == "lld"
+    then null
+    else pkgs.bintoolsNoLibc
+, bootBintools ?
+    if stdenv.targetPlatform.linker == "lld"
+    then null
+    else pkgs.bintools
+, darwin
+}:
+
+let
+  release_version = "12.0.0";
+  candidate = ""; # empty or "rcN"
+  dash-candidate = lib.optionalString (candidate != "") "-${candidate}";
+  version = "${release_version}${dash-candidate}"; # differentiating these (variables) is important for RCs
+  targetConfig = stdenv.targetPlatform.config;
+
+  src = fetchFromGitHub {
+    owner = "llvm";
+    repo = "llvm-project";
+    rev = "llvmorg-${version}";
+    sha256 = "07jz8pywc2qqa1srdnqg5p2y4lx3ki1inpigarzgxc3j20r4gb58";
+  };
+
+  llvm_meta = {
+    license     = lib.licenses.ncsa;
+    maintainers = with lib.maintainers; [ lovek323 raskin dtzWill primeos ];
+    platforms   = lib.platforms.all;
+  };
+
+  tools = lib.makeExtensible (tools: let
+    callPackage = newScope (tools // { inherit stdenv cmake libxml2 python3 isl release_version version src buildLlvmTools; });
+    mkExtraBuildCommands0 = cc: ''
+      rsrc="$out/resource-root"
+      mkdir "$rsrc"
+      ln -s "${cc.lib}/lib/clang/${release_version}/include" "$rsrc"
+      echo "-resource-dir=$rsrc" >> $out/nix-support/cc-cflags
+    '';
+    mkExtraBuildCommands = cc: mkExtraBuildCommands0 cc + ''
+      ln -s "${targetLlvmLibraries.compiler-rt.out}/lib" "$rsrc/lib"
+      ln -s "${targetLlvmLibraries.compiler-rt.out}/share" "$rsrc/share"
+    '';
+
+  bintoolsNoLibc' =
+    if bootBintoolsNoLibc == null
+    then tools.bintoolsNoLibc
+    else bootBintoolsNoLibc;
+  bintools' =
+    if bootBintools == null
+    then tools.bintools
+    else bootBintools;
+
+  in {
+
+    libllvm = callPackage ./llvm {
+      inherit llvm_meta;
+    };
+
+    # `llvm` historically had the binaries.  When choosing an output explicitly,
+    # we need to reintroduce `outputUnspecified` to get the expected behavior e.g. of lib.get*
+    llvm = tools.libllvm.out // { outputUnspecified = true; };
+
+    libclang = callPackage ./clang {
+      inherit llvm_meta;
+    };
+
+    clang-unwrapped = tools.libclang.out // { outputUnspecified = true; };
+
+    # disabled until recommonmark supports sphinx 3
+    #Llvm-manpages = lowPrio (tools.libllvm.override {
+    #  enableManpages = true;
+    #  python3 = pkgs.python3;  # don't use python-boot
+    #});
+
+    clang-manpages = lowPrio (tools.libclang.override {
+      enableManpages = true;
+      python3 = pkgs.python3;  # don't use python-boot
+    });
+
+    # disabled until recommonmark supports sphinx 3
+    # lldb-manpages = lowPrio (tools.lldb.override {
+    #   enableManpages = true;
+    #   python3 = pkgs.python3;  # don't use python-boot
+    # });
+
+    clang = if stdenv.cc.isGNU then tools.libstdcxxClang else tools.libcxxClang;
+
+    libstdcxxClang = wrapCCWith rec {
+      cc = tools.clang-unwrapped;
+      # libstdcxx is taken from gcc in an ad-hoc way in cc-wrapper.
+      libcxx = null;
+      extraPackages = [
+        targetLlvmLibraries.compiler-rt
+      ];
+      extraBuildCommands = mkExtraBuildCommands cc;
+    };
+
+    libcxxClang = wrapCCWith rec {
+      cc = tools.clang-unwrapped;
+      libcxx = targetLlvmLibraries.libcxx;
+      extraPackages = [
+        targetLlvmLibraries.libcxxabi
+        targetLlvmLibraries.compiler-rt
+      ];
+      extraBuildCommands = mkExtraBuildCommands cc;
+    };
+
+    lld = callPackage ./lld {
+      inherit llvm_meta;
+    };
+
+    lldb = callPackage ./lldb {
+      inherit llvm_meta;
+      inherit (darwin) libobjc bootstrap_cmds;
+      inherit (darwin.apple_sdk.libs) xpc;
+      inherit (darwin.apple_sdk.frameworks) Foundation Carbon Cocoa;
+    };
+
+    # Below, is the LLVM bootstrapping logic. It handles building a
+    # fully LLVM toolchain from scratch. No GCC toolchain should be
+    # pulled in. As a consequence, it is very quick to build different
+    # targets provided by LLVM and we can also build for what GCC
+    # doesn’t support like LLVM. Probably we should move to some other
+    # file.
+
+    bintools-unwrapped = callPackage ./bintools {};
+
+    bintoolsNoLibc = wrapBintoolsWith {
+      bintools = tools.bintools-unwrapped;
+      libc = preLibcCrossHeaders;
+    };
+
+    bintools = wrapBintoolsWith {
+      bintools = tools.bintools-unwrapped;
+    };
+
+    clangUseLLVM = wrapCCWith rec {
+      cc = tools.clang-unwrapped;
+      libcxx = targetLlvmLibraries.libcxx;
+      bintools = bintools';
+      extraPackages = [
+        targetLlvmLibraries.libcxxabi
+        targetLlvmLibraries.compiler-rt
+      ] ++ lib.optionals (!stdenv.targetPlatform.isWasm) [
+        targetLlvmLibraries.libunwind
+      ];
+      extraBuildCommands = ''
+        echo "-rtlib=compiler-rt -Wno-unused-command-line-argument" >> $out/nix-support/cc-cflags
+        echo "-B${targetLlvmLibraries.compiler-rt}/lib" >> $out/nix-support/cc-cflags
+      '' + lib.optionalString (!stdenv.targetPlatform.isWasm) ''
+        echo "--unwindlib=libunwind" >> $out/nix-support/cc-cflags
+      '' + lib.optionalString (!stdenv.targetPlatform.isWasm && stdenv.targetPlatform.useLLVM or false) ''
+        echo "-lunwind" >> $out/nix-support/cc-ldflags
+      '' + lib.optionalString stdenv.targetPlatform.isWasm ''
+        echo "-fno-exceptions" >> $out/nix-support/cc-cflags
+      '' + mkExtraBuildCommands cc;
+    };
+
+    clangNoLibcxx = wrapCCWith rec {
+      cc = tools.clang-unwrapped;
+      libcxx = null;
+      bintools = bintools';
+      extraPackages = [
+        targetLlvmLibraries.compiler-rt
+      ];
+      extraBuildCommands = ''
+        echo "-rtlib=compiler-rt" >> $out/nix-support/cc-cflags
+        echo "-B${targetLlvmLibraries.compiler-rt}/lib" >> $out/nix-support/cc-cflags
+        echo "-nostdlib++" >> $out/nix-support/cc-cflags
+      '' + mkExtraBuildCommands cc;
+    };
+
+    clangNoLibc = wrapCCWith rec {
+      cc = tools.clang-unwrapped;
+      libcxx = null;
+      bintools = bintoolsNoLibc';
+      extraPackages = [
+        targetLlvmLibraries.compiler-rt
+      ];
+      extraBuildCommands = ''
+        echo "-rtlib=compiler-rt" >> $out/nix-support/cc-cflags
+        echo "-B${targetLlvmLibraries.compiler-rt}/lib" >> $out/nix-support/cc-cflags
+      '' + mkExtraBuildCommands cc;
+    };
+
+    clangNoCompilerRt = wrapCCWith rec {
+      cc = tools.clang-unwrapped;
+      libcxx = null;
+      bintools = bintoolsNoLibc';
+      extraPackages = [ ];
+      extraBuildCommands = ''
+        echo "-nostartfiles" >> $out/nix-support/cc-cflags
+      '' + mkExtraBuildCommands0 cc;
+    };
+
+    clangNoCompilerRtWithLibc = wrapCCWith rec {
+      cc = tools.clang-unwrapped;
+      libcxx = null;
+      bintools = bintools';
+      extraPackages = [ ];
+      extraBuildCommands = mkExtraBuildCommands0 cc;
+    };
+
+  });
+
+  libraries = lib.makeExtensible (libraries: let
+    callPackage = newScope (libraries // buildLlvmTools // { inherit stdenv cmake libxml2 python3 isl release_version version src; });
+  in {
+
+    compiler-rt-libc = callPackage ./compiler-rt {
+      inherit llvm_meta;
+      stdenv = if stdenv.hostPlatform.useLLVM or false
+               then overrideCC stdenv buildLlvmTools.clangNoCompilerRtWithLibc
+               else stdenv;
+    };
+
+    compiler-rt-no-libc = callPackage ./compiler-rt {
+      inherit llvm_meta;
+      stdenv = if stdenv.hostPlatform.useLLVM or false
+               then overrideCC stdenv buildLlvmTools.clangNoCompilerRt
+               else stdenv;
+    };
+
+    # N.B. condition is safe because without useLLVM both are the same.
+    compiler-rt = if stdenv.hostPlatform.isAndroid
+      then libraries.compiler-rt-libc
+      else libraries.compiler-rt-no-libc;
+
+    stdenv = overrideCC stdenv buildLlvmTools.clang;
+
+    libcxxStdenv = overrideCC stdenv buildLlvmTools.libcxxClang;
+
+    libcxx = callPackage ./libcxx {
+      inherit llvm_meta;
+      stdenv = if stdenv.hostPlatform.useLLVM or false
+               then overrideCC stdenv buildLlvmTools.clangNoLibcxx
+               else stdenv;
+    };
+
+    libcxxabi = callPackage ./libcxxabi {
+      inherit llvm_meta;
+      stdenv = if stdenv.hostPlatform.useLLVM or false
+               then overrideCC stdenv buildLlvmTools.clangNoLibcxx
+               else stdenv;
+    };
+
+    libunwind = callPackage ./libunwind {
+      inherit llvm_meta;
+      stdenv = if stdenv.hostPlatform.useLLVM or false
+               then overrideCC stdenv buildLlvmTools.clangNoLibcxx
+               else stdenv;
+    };
+
+    openmp = callPackage ./openmp {
+      inherit llvm_meta;
+    };
+  });
+
+in { inherit tools libraries; } // libraries // tools
diff --git a/pkgs/development/compilers/llvm/git/libcxx/default.nix b/pkgs/development/compilers/llvm/git/libcxx/default.nix
new file mode 100644
index 000000000000..8fb6b4a7dbd4
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/libcxx/default.nix
@@ -0,0 +1,54 @@
+{ lib, stdenv, llvm_meta, src, cmake, python3, libcxxabi, fixDarwinDylibNames, version
+, enableShared ? !stdenv.hostPlatform.isStatic
+}:
+
+stdenv.mkDerivation rec {
+  pname = "libcxx";
+  inherit version;
+
+  inherit src;
+  sourceRoot = "source/${pname}";
+
+  outputs = [ "out" "dev" ];
+
+  patches = [
+    ./gnu-install-dirs.patch
+  ] ++ lib.optionals stdenv.hostPlatform.isMusl [
+    ../../libcxx-0001-musl-hacks.patch
+  ];
+
+  preConfigure = lib.optionalString stdenv.hostPlatform.isMusl ''
+    patchShebangs utils/cat_files.py
+  '';
+
+  nativeBuildInputs = [ cmake python3 ]
+    ++ lib.optional stdenv.isDarwin fixDarwinDylibNames;
+
+  buildInputs = [ libcxxabi ];
+
+  cmakeFlags = [
+    "-DLIBCXX_CXX_ABI=libcxxabi"
+  ] ++ lib.optional (stdenv.hostPlatform.isMusl || stdenv.hostPlatform.isWasi) "-DLIBCXX_HAS_MUSL_LIBC=1"
+    ++ lib.optional (stdenv.hostPlatform.useLLVM or false) "-DLIBCXX_USE_COMPILER_RT=ON"
+    ++ lib.optional stdenv.hostPlatform.isWasm [
+      "-DLIBCXX_ENABLE_THREADS=OFF"
+      "-DLIBCXX_ENABLE_FILESYSTEM=OFF"
+      "-DLIBCXX_ENABLE_EXCEPTIONS=OFF"
+    ] ++ lib.optional (!enableShared) "-DLIBCXX_ENABLE_SHARED=OFF";
+
+  passthru = {
+    isLLVM = true;
+  };
+
+  meta = llvm_meta // {
+    homepage = "https://libcxx.llvm.org/";
+    description = "C++ standard library";
+    longDescription = ''
+      libc++ is an implementation of the C++ standard library, targeting C++11,
+      C++14 and above.
+    '';
+    # "All of the code in libc++ is dual licensed under the MIT license and the
+    # UIUC License (a BSD-like license)":
+    license = with lib.licenses; [ mit ncsa ];
+  };
+}
diff --git a/pkgs/development/compilers/llvm/git/libcxx/gnu-install-dirs.patch b/pkgs/development/compilers/llvm/git/libcxx/gnu-install-dirs.patch
new file mode 100644
index 000000000000..1f9de00a9d56
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/libcxx/gnu-install-dirs.patch
@@ -0,0 +1,100 @@
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index 9bf1a02f0908..612cd4aab76c 100644
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -28,6 +28,8 @@ set(LIBCXX_BINARY_INCLUDE_DIR "${LIBCXX_BINARY_DIR}/include/c++build")
+ if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR OR LIBCXX_STANDALONE_BUILD)
+   project(libcxx CXX C)
+ 
++  include(GNUInstallDirs)
++
+   set(PACKAGE_NAME libcxx)
+   set(PACKAGE_VERSION 12.0.0)
+   set(PACKAGE_STRING "${PACKAGE_NAME} ${PACKAGE_VERSION}")
+@@ -402,7 +404,7 @@ endif ()
+ if(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR AND NOT APPLE)
+   set(LIBCXX_LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR}/${LLVM_DEFAULT_TARGET_TRIPLE}/c++)
+   set(LIBCXX_HEADER_DIR ${LLVM_BINARY_DIR})
+-  set(LIBCXX_INSTALL_LIBRARY_DIR lib${LLVM_LIBDIR_SUFFIX}/${LLVM_DEFAULT_TARGET_TRIPLE}/c++)
++  set(LIBCXX_INSTALL_LIBRARY_DIR ${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}/${LLVM_DEFAULT_TARGET_TRIPLE}/c++)
+   if(LIBCXX_LIBDIR_SUBDIR)
+     string(APPEND LIBCXX_LIBRARY_DIR /${LIBCXX_LIBDIR_SUBDIR})
+     string(APPEND LIBCXX_INSTALL_LIBRARY_DIR /${LIBCXX_LIBDIR_SUBDIR})
+@@ -410,11 +412,11 @@ if(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR AND NOT APPLE)
+ elseif(LLVM_LIBRARY_OUTPUT_INTDIR)
+   set(LIBCXX_LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR})
+   set(LIBCXX_HEADER_DIR  ${LLVM_BINARY_DIR})
+-  set(LIBCXX_INSTALL_LIBRARY_DIR lib${LIBCXX_LIBDIR_SUFFIX})
++  set(LIBCXX_INSTALL_LIBRARY_DIR ${CMAKE_INSTALL_LIBDIR}${LIBCXX_LIBDIR_SUFFIX})
+ else()
+   set(LIBCXX_LIBRARY_DIR ${CMAKE_BINARY_DIR}/lib${LIBCXX_LIBDIR_SUFFIX})
+   set(LIBCXX_HEADER_DIR  ${CMAKE_BINARY_DIR})
+-  set(LIBCXX_INSTALL_LIBRARY_DIR lib${LIBCXX_LIBDIR_SUFFIX})
++  set(LIBCXX_INSTALL_LIBRARY_DIR ${CMAKE_INSTALL_LIBDIR}${LIBCXX_LIBDIR_SUFFIX})
+ endif()
+ 
+ file(MAKE_DIRECTORY "${LIBCXX_BINARY_INCLUDE_DIR}")
+diff --git a/cmake/Modules/HandleLibCXXABI.cmake b/cmake/Modules/HandleLibCXXABI.cmake
+index 5d2764e870e9..bb1ec5de6ca2 100644
+--- a/cmake/Modules/HandleLibCXXABI.cmake
++++ b/cmake/Modules/HandleLibCXXABI.cmake
+@@ -63,7 +63,7 @@ macro(setup_abi_lib abidefines abishared abistatic abifiles abidirs)
+ 
+         if (LIBCXX_INSTALL_HEADERS)
+           install(FILES "${LIBCXX_BINARY_INCLUDE_DIR}/${fpath}"
+-            DESTINATION ${LIBCXX_INSTALL_HEADER_PREFIX}include/c++/v1/${dstdir}
++            DESTINATION ${LIBCXX_INSTALL_HEADER_PREFIX}${CMAKE_INSTALL_INCLUDEDIR}/c++/v1/${dstdir}
+             COMPONENT cxx-headers
+             PERMISSIONS OWNER_READ OWNER_WRITE GROUP_READ WORLD_READ
+             )
+diff --git a/include/CMakeLists.txt b/include/CMakeLists.txt
+index 29a317b8ae9a..4747263cfd1b 100644
+--- a/include/CMakeLists.txt
++++ b/include/CMakeLists.txt
+@@ -252,7 +252,7 @@ if (LIBCXX_INSTALL_HEADERS)
+   foreach(file ${files})
+     get_filename_component(dir ${file} DIRECTORY)
+     install(FILES ${file}
+-      DESTINATION ${LIBCXX_INSTALL_HEADER_PREFIX}include/c++/v1/${dir}
++      DESTINATION ${LIBCXX_INSTALL_HEADER_PREFIX}${CMAKE_INSTALL_INCLUDEDIR}/c++/v1/${dir}
+       COMPONENT cxx-headers
+       PERMISSIONS OWNER_READ OWNER_WRITE GROUP_READ WORLD_READ
+     )
+@@ -260,7 +260,7 @@ if (LIBCXX_INSTALL_HEADERS)
+ 
+   # Install the generated header as __config.
+   install(FILES ${LIBCXX_BINARY_DIR}/__generated_config
+-    DESTINATION ${LIBCXX_INSTALL_HEADER_PREFIX}include/c++/v1
++    DESTINATION ${LIBCXX_INSTALL_HEADER_PREFIX}${CMAKE_INSTALL_INCLUDEDIR}/c++/v1
+     PERMISSIONS OWNER_READ OWNER_WRITE GROUP_READ WORLD_READ
+     RENAME __config
+     COMPONENT cxx-headers)
+diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
+index 9965104cb5b2..9b55dbb1d822 100644
+--- a/src/CMakeLists.txt
++++ b/src/CMakeLists.txt
+@@ -352,21 +352,21 @@ if (LIBCXX_INSTALL_SHARED_LIBRARY)
+   install(TARGETS cxx_shared
+     ARCHIVE DESTINATION ${LIBCXX_INSTALL_PREFIX}${LIBCXX_INSTALL_LIBRARY_DIR} COMPONENT cxx
+     LIBRARY DESTINATION ${LIBCXX_INSTALL_PREFIX}${LIBCXX_INSTALL_LIBRARY_DIR} COMPONENT cxx
+-    RUNTIME DESTINATION ${LIBCXX_INSTALL_PREFIX}bin COMPONENT cxx)
++    RUNTIME DESTINATION ${LIBCXX_INSTALL_PREFIX}${CMAKE_INSTALL_BINDIR} COMPONENT cxx)
+ endif()
+ 
+ if (LIBCXX_INSTALL_STATIC_LIBRARY)
+   install(TARGETS cxx_static
+     ARCHIVE DESTINATION ${LIBCXX_INSTALL_PREFIX}${LIBCXX_INSTALL_LIBRARY_DIR} COMPONENT cxx
+     LIBRARY DESTINATION ${LIBCXX_INSTALL_PREFIX}${LIBCXX_INSTALL_LIBRARY_DIR} COMPONENT cxx
+-    RUNTIME DESTINATION ${LIBCXX_INSTALL_PREFIX}bin COMPONENT cxx)
++    RUNTIME DESTINATION ${LIBCXX_INSTALL_PREFIX}${CMAKE_INSTALL_BINDIR} COMPONENT cxx)
+ endif()
+ 
+ if(LIBCXX_INSTALL_EXPERIMENTAL_LIBRARY)
+   install(TARGETS cxx_experimental
+     LIBRARY DESTINATION ${LIBCXX_INSTALL_PREFIX}${LIBCXX_INSTALL_LIBRARY_DIR} COMPONENT cxx
+     ARCHIVE DESTINATION ${LIBCXX_INSTALL_PREFIX}${LIBCXX_INSTALL_LIBRARY_DIR} COMPONENT cxx
+-    RUNTIME DESTINATION ${LIBCXX_INSTALL_PREFIX}bin COMPONENT cxx)
++    RUNTIME DESTINATION ${LIBCXX_INSTALL_PREFIX}${CMAKE_INSTALL_BINDIR} COMPONENT cxx)
+ endif()
+ 
+ # NOTE: This install command must go after the cxx install command otherwise
diff --git a/pkgs/development/compilers/llvm/git/libcxxabi/default.nix b/pkgs/development/compilers/llvm/git/libcxxabi/default.nix
new file mode 100644
index 000000000000..3bb82d651ec7
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/libcxxabi/default.nix
@@ -0,0 +1,73 @@
+{ lib, stdenv, llvm_meta, cmake, python3, src, libunwind, version
+, enableShared ? !stdenv.hostPlatform.isStatic
+}:
+
+stdenv.mkDerivation rec {
+  pname = "libcxxabi";
+  inherit version;
+
+  inherit src;
+  sourceRoot = "source/${pname}";
+
+  outputs = [ "out" "dev" ];
+
+  postUnpack = lib.optionalString stdenv.isDarwin ''
+    export TRIPLE=x86_64-apple-darwin
+  '' + lib.optionalString stdenv.hostPlatform.isMusl ''
+    patch -p1 -d libcxx -i ${../../libcxx-0001-musl-hacks.patch}
+  '' + lib.optionalString stdenv.hostPlatform.isWasm ''
+    patch -p1 -d llvm -i ${./wasm.patch}
+  '';
+
+  patches = [
+    ./gnu-install-dirs.patch
+  ];
+
+  nativeBuildInputs = [ cmake python3 ];
+  buildInputs = lib.optional (!stdenv.isDarwin && !stdenv.isFreeBSD && !stdenv.hostPlatform.isWasm) libunwind;
+
+  cmakeFlags = lib.optionals (stdenv.hostPlatform.useLLVM or false) [
+    "-DLLVM_ENABLE_LIBCXX=ON"
+    "-DLIBCXXABI_USE_LLVM_UNWINDER=ON"
+  ] ++ lib.optionals stdenv.hostPlatform.isWasm [
+    "-DLIBCXXABI_ENABLE_THREADS=OFF"
+    "-DLIBCXXABI_ENABLE_EXCEPTIONS=OFF"
+  ] ++ lib.optionals (!enableShared) [
+    "-DLIBCXXABI_ENABLE_SHARED=OFF"
+  ];
+
+  installPhase = if stdenv.isDarwin
+    then ''
+      for file in lib/*.dylib; do
+        # this should be done in CMake, but having trouble figuring out
+        # the magic combination of necessary CMake variables
+        # if you fancy a try, take a look at
+        # https://gitlab.kitware.com/cmake/community/-/wikis/doc/cmake/RPATH-handling
+        install_name_tool -id $out/$file $file
+      done
+      make install
+      install -d 755 $out/include
+      install -m 644 ../include/*.h $out/include
+    ''
+    else ''
+      install -d -m 755 $out/include $out/lib
+      install -m 644 lib/libc++abi.a $out/lib
+      install -m 644 ../include/cxxabi.h $out/include
+    '' + lib.optionalString enableShared ''
+      install -m 644 lib/libc++abi.so.1.0 $out/lib
+      ln -s libc++abi.so.1.0 $out/lib/libc++abi.so
+      ln -s libc++abi.so.1.0 $out/lib/libc++abi.so.1
+    '';
+
+  meta = llvm_meta // {
+    homepage = "https://libcxxabi.llvm.org/";
+    description = "Provides C++ standard library support";
+    longDescription = ''
+      libc++abi is a new implementation of low level support for a standard C++ library.
+    '';
+    # "All of the code in libc++abi is dual licensed under the MIT license and
+    # the UIUC License (a BSD-like license)":
+    license = with lib.licenses; [ mit ncsa ];
+    maintainers = llvm_meta.maintainers ++ [ lib.maintainers.vlstill ];
+  };
+}
diff --git a/pkgs/development/compilers/llvm/git/libcxxabi/gnu-install-dirs.patch b/pkgs/development/compilers/llvm/git/libcxxabi/gnu-install-dirs.patch
new file mode 100644
index 000000000000..b49b1685940f
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/libcxxabi/gnu-install-dirs.patch
@@ -0,0 +1,34 @@
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index 426c855288fc..a9812a994f53 100644
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -27,6 +27,8 @@ set(LIBCXXABI_LIBCXX_PATH "${CMAKE_CURRENT_LIST_DIR}/../libcxx" CACHE PATH
+ if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR OR LIBCXXABI_STANDALONE_BUILD)
+   project(libcxxabi CXX C)
+ 
++  include(GNUInstallDirs)
++
+   set(PACKAGE_NAME libcxxabi)
+   set(PACKAGE_VERSION 11.0.0)
+   set(PACKAGE_STRING "${PACKAGE_NAME} ${PACKAGE_VERSION}")
+@@ -180,17 +182,17 @@ set(CMAKE_MODULE_PATH
+ 
+ if(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR AND NOT APPLE)
+   set(LIBCXXABI_LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR}/${LLVM_DEFAULT_TARGET_TRIPLE}/c++)
+-  set(LIBCXXABI_INSTALL_LIBRARY_DIR lib${LLVM_LIBDIR_SUFFIX}/${LLVM_DEFAULT_TARGET_TRIPLE}/c++)
++  set(LIBCXXABI_INSTALL_LIBRARY_DIR ${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}/${LLVM_DEFAULT_TARGET_TRIPLE}/c++)
+   if(LIBCXX_LIBDIR_SUBDIR)
+     string(APPEND LIBCXXABI_LIBRARY_DIR /${LIBCXXABI_LIBDIR_SUBDIR})
+     string(APPEND LIBCXXABI_INSTALL_LIBRARY_DIR /${LIBCXXABI_LIBDIR_SUBDIR})
+   endif()
+ elseif(LLVM_LIBRARY_OUTPUT_INTDIR)
+   set(LIBCXXABI_LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR})
+-  set(LIBCXXABI_INSTALL_LIBRARY_DIR lib${LIBCXXABI_LIBDIR_SUFFIX})
++  set(LIBCXXABI_INSTALL_LIBRARY_DIR ${CMAKE_INSTALL_LIBDIR}${LIBCXXABI_LIBDIR_SUFFIX})
+ else()
+   set(LIBCXXABI_LIBRARY_DIR ${CMAKE_BINARY_DIR}/lib${LIBCXXABI_LIBDIR_SUFFIX})
+-  set(LIBCXXABI_INSTALL_LIBRARY_DIR lib${LIBCXXABI_LIBDIR_SUFFIX})
++  set(LIBCXXABI_INSTALL_LIBRARY_DIR ${CMAKE_INSTALL_LIBDIR}${LIBCXXABI_LIBDIR_SUFFIX})
+ endif()
+ 
+ set(LIBCXXABI_INSTALL_PREFIX "" CACHE STRING "Define libc++abi destination prefix.")
diff --git a/pkgs/development/compilers/llvm/git/libcxxabi/wasm.patch b/pkgs/development/compilers/llvm/git/libcxxabi/wasm.patch
new file mode 100644
index 000000000000..4ebfe46aa813
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/libcxxabi/wasm.patch
@@ -0,0 +1,16 @@
+diff --git a/cmake/modules/HandleLLVMOptions.cmake b/cmake/modules/HandleLLVMOptions.cmake
+index 15497d405e0..33f7f18193a 100644
+--- a/cmake/modules/HandleLLVMOptions.cmake
++++ b/cmake/modules/HandleLLVMOptions.cmake
+@@ -127,7 +127,10 @@ else(WIN32)
+       set(LLVM_HAVE_LINK_VERSION_SCRIPT 1)
+     endif()
+   else(FUCHSIA OR UNIX)
+-    MESSAGE(SEND_ERROR "Unable to determine platform")
++    if(${CMAKE_SYSTEM_NAME} MATCHES "Wasi")
++    else()
++      MESSAGE(SEND_ERROR "Unable to determine platform")
++    endif()
+   endif(FUCHSIA OR UNIX)
+ endif(WIN32)
+ 
diff --git a/pkgs/development/compilers/llvm/git/libunwind/default.nix b/pkgs/development/compilers/llvm/git/libunwind/default.nix
new file mode 100644
index 000000000000..b6017e741728
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/libunwind/default.nix
@@ -0,0 +1,33 @@
+{ lib, stdenv, llvm_meta, version, src, cmake
+, enableShared ? !stdenv.hostPlatform.isStatic
+}:
+
+stdenv.mkDerivation rec {
+  pname = "libunwind";
+  inherit version;
+
+  inherit src;
+  sourceRoot = "source/${pname}";
+
+  patches = [
+    ./gnu-install-dirs.patch
+  ];
+
+  outputs = [ "out" "dev" ];
+
+  nativeBuildInputs = [ cmake ];
+
+  cmakeFlags = lib.optional (!enableShared) "-DLIBUNWIND_ENABLE_SHARED=OFF";
+
+  meta = llvm_meta // {
+    # Details: https://github.com/llvm/llvm-project/blob/main/libunwind/docs/index.rst
+    homepage = "https://clang.llvm.org/docs/Toolchain.html#unwind-library";
+    description = "LLVM's unwinder library";
+    longDescription = ''
+      The unwind library provides a family of _Unwind_* functions implementing
+      the language-neutral stack unwinding portion of the Itanium C++ ABI (Level
+      I). It is a dependency of the C++ ABI library, and sometimes is a
+      dependency of other runtimes.
+    '';
+  };
+}
diff --git a/pkgs/development/compilers/llvm/git/libunwind/gnu-install-dirs.patch b/pkgs/development/compilers/llvm/git/libunwind/gnu-install-dirs.patch
new file mode 100644
index 000000000000..a791d6c43231
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/libunwind/gnu-install-dirs.patch
@@ -0,0 +1,34 @@
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index 48cb8e004e08..fec8144fb95a 100644
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -23,6 +23,8 @@ set(LIBUNWIND_LIBCXX_PATH "${CMAKE_CURRENT_LIST_DIR}/../libcxx" CACHE PATH
+ if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR OR LIBUNWIND_STANDALONE_BUILD)
+   project(libunwind LANGUAGES C CXX ASM)
+ 
++  include(GNUInstallDirs)
++
+   set(PACKAGE_NAME libunwind)
+   set(PACKAGE_VERSION 12.0.0)
+   set(PACKAGE_STRING "${PACKAGE_NAME} ${PACKAGE_VERSION}")
+@@ -115,17 +117,17 @@ set(CMAKE_MODULE_PATH
+ 
+ if(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR AND NOT APPLE)
+   set(LIBUNWIND_LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR}/${LLVM_DEFAULT_TARGET_TRIPLE}/c++)
+-  set(LIBUNWIND_INSTALL_LIBRARY_DIR lib${LLVM_LIBDIR_SUFFIX}/${LLVM_DEFAULT_TARGET_TRIPLE}/c++)
++  set(LIBUNWIND_INSTALL_LIBRARY_DIR ${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}/${LLVM_DEFAULT_TARGET_TRIPLE}/c++)
+   if(LIBCXX_LIBDIR_SUBDIR)
+     string(APPEND LIBUNWIND_LIBRARY_DIR /${LIBUNWIND_LIBDIR_SUBDIR})
+     string(APPEND LIBUNWIND_INSTALL_LIBRARY_DIR /${LIBUNWIND_LIBDIR_SUBDIR})
+   endif()
+ elseif(LLVM_LIBRARY_OUTPUT_INTDIR)
+   set(LIBUNWIND_LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR})
+-  set(LIBUNWIND_INSTALL_LIBRARY_DIR lib${LIBUNWIND_LIBDIR_SUFFIX})
++  set(LIBUNWIND_INSTALL_LIBRARY_DIR ${CMAKE_INSTALL_LIBDIR}${LIBUNWIND_LIBDIR_SUFFIX})
+ else()
+   set(LIBUNWIND_LIBRARY_DIR ${CMAKE_BINARY_DIR}/lib${LIBUNWIND_LIBDIR_SUFFIX})
+-  set(LIBUNWIND_INSTALL_LIBRARY_DIR lib${LIBUNWIND_LIBDIR_SUFFIX})
++  set(LIBUNWIND_INSTALL_LIBRARY_DIR ${CMAKE_INSTALL_LIBDIR}${LIBUNWIND_LIBDIR_SUFFIX})
+ endif()
+ 
+ set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${LIBUNWIND_LIBRARY_DIR})
diff --git a/pkgs/development/compilers/llvm/git/lld/default.nix b/pkgs/development/compilers/llvm/git/lld/default.nix
new file mode 100644
index 000000000000..34ac265f4bfd
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/lld/default.nix
@@ -0,0 +1,44 @@
+{ lib, stdenv, llvm_meta
+, buildLlvmTools
+, src
+, cmake
+, libxml2
+, libllvm
+, version
+}:
+
+stdenv.mkDerivation rec {
+  pname = "lld";
+  inherit version;
+
+  inherit src;
+  sourceRoot = "source/${pname}";
+
+  patches = [
+    ./gnu-install-dirs.patch
+  ];
+
+  nativeBuildInputs = [ cmake ];
+  buildInputs = [ libllvm libxml2 ];
+
+  cmakeFlags = [
+    "-DLLVM_CONFIG_PATH=${libllvm.dev}/bin/llvm-config${lib.optionalString (stdenv.hostPlatform != stdenv.buildPlatform) "-native"}"
+  ] ++ lib.optionals (stdenv.hostPlatform != stdenv.buildPlatform) [
+    "-DLLVM_TABLEGEN_EXE=${buildLlvmTools.llvm}/bin/llvm-tblgen"
+  ];
+
+  outputs = [ "out" "lib" "dev" ];
+
+  meta = llvm_meta // {
+    homepage = "https://lld.llvm.org/";
+    description = "The LLVM linker";
+    longDescription = ''
+      LLD is a linker from the LLVM project that is a drop-in replacement for
+      system linkers and runs much faster than them. It also provides features
+      that are useful for toolchain developers.
+      The linker supports ELF (Unix), PE/COFF (Windows), Mach-O (macOS), and
+      WebAssembly in descending order of completeness. Internally, LLD consists
+      of several different linkers.
+    '';
+  };
+}
diff --git a/pkgs/development/compilers/llvm/git/lld/gnu-install-dirs.patch b/pkgs/development/compilers/llvm/git/lld/gnu-install-dirs.patch
new file mode 100644
index 000000000000..61e2f0e48653
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/lld/gnu-install-dirs.patch
@@ -0,0 +1,68 @@
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index d4e561b50d8f..cfa5bdd79c2a 100644
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -6,6 +6,8 @@ if(CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
+   set(CMAKE_INCLUDE_CURRENT_DIR ON)
+   set(LLD_BUILT_STANDALONE TRUE)
+ 
++  include(GNUInstallDirs)
++
+   find_program(LLVM_CONFIG_PATH "llvm-config" DOC "Path to llvm-config binary")
+   if(NOT LLVM_CONFIG_PATH)
+     message(FATAL_ERROR "llvm-config not found: specify LLVM_CONFIG_PATH")
+@@ -179,7 +181,7 @@ include_directories(BEFORE
+ 
+ if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
+   install(DIRECTORY include/
+-    DESTINATION include
++    DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
+     FILES_MATCHING
+     PATTERN "*.h"
+     )
+diff --git a/cmake/modules/AddLLD.cmake b/cmake/modules/AddLLD.cmake
+index 23df41312403..d62372c88de7 100644
+--- a/cmake/modules/AddLLD.cmake
++++ b/cmake/modules/AddLLD.cmake
+@@ -20,9 +20,9 @@ macro(add_lld_library name)
+     install(TARGETS ${name}
+       COMPONENT ${name}
+       ${export_to_lldtargets}
+-      LIBRARY DESTINATION lib${LLVM_LIBDIR_SUFFIX}
+-      ARCHIVE DESTINATION lib${LLVM_LIBDIR_SUFFIX}
+-      RUNTIME DESTINATION bin)
++      LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}
++      ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}
++      RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
+ 
+     if (${ARG_SHARED} AND NOT CMAKE_CONFIGURATION_TYPES)
+       add_llvm_install_targets(install-${name}
+@@ -54,7 +54,7 @@ macro(add_lld_tool name)
+ 
+     install(TARGETS ${name}
+       ${export_to_lldtargets}
+-      RUNTIME DESTINATION bin
++      RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
+       COMPONENT ${name})
+ 
+     if(NOT CMAKE_CONFIGURATION_TYPES)
+@@ -69,5 +69,5 @@ endmacro()
+ macro(add_lld_symlink name dest)
+   add_llvm_tool_symlink(${name} ${dest} ALWAYS_GENERATE)
+   # Always generate install targets
+-  llvm_install_symlink(${name} ${dest} ALWAYS_GENERATE)
++  llvm_install_symlink(${name} ${dest} ${CMAKE_INSTALL_FULL_BINDIR} ALWAYS_GENERATE)
+ endmacro()
+diff --git a/tools/lld/CMakeLists.txt b/tools/lld/CMakeLists.txt
+index 5cff736ff57f..64e775c771b9 100644
+--- a/tools/lld/CMakeLists.txt
++++ b/tools/lld/CMakeLists.txt
+@@ -21,7 +21,7 @@ target_link_libraries(lld
+   )
+ 
+ install(TARGETS lld
+-  RUNTIME DESTINATION bin)
++  RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
+ 
+ if(NOT LLD_SYMLINKS_TO_CREATE)
+   set(LLD_SYMLINKS_TO_CREATE
diff --git a/pkgs/development/compilers/llvm/git/lldb/default.nix b/pkgs/development/compilers/llvm/git/lldb/default.nix
new file mode 100644
index 000000000000..f8c7e7b55e67
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/lldb/default.nix
@@ -0,0 +1,131 @@
+{ lib, stdenv, llvm_meta
+, runCommand
+, src
+, cmake
+, zlib
+, ncurses
+, swig
+, which
+, libedit
+, libxml2
+, libllvm
+, libclang
+, python3
+, version
+, libobjc
+, xpc
+, Foundation
+, bootstrap_cmds
+, Carbon
+, Cocoa
+, lit
+, enableManpages ? false
+}:
+
+stdenv.mkDerivation (rec {
+  pname = "lldb";
+  inherit version;
+
+  inherit src;
+  sourceRoot = "source/${pname}";
+
+  patches = [
+    ./procfs.patch
+    (runCommand "resource-dir.patch" {
+      clangLibDir = "${libclang.lib}/lib";
+    } ''
+      substitute '${./resource-dir.patch}' "$out" --subst-var clangLibDir
+    '')
+    ./gnu-install-dirs.patch
+  ];
+
+  outputs = [ "out" "lib" "dev" ];
+
+  nativeBuildInputs = [
+    cmake python3 which swig lit
+  ] ++ lib.optionals enableManpages [
+    python3.pkgs.sphinx python3.pkgs.recommonmark
+  ];
+
+  buildInputs = [
+    ncurses
+    zlib
+    libedit
+    libxml2
+    libllvm
+  ]
+  ++ lib.optionals stdenv.isDarwin [
+    libobjc
+    xpc
+    Foundation
+    bootstrap_cmds
+    Carbon
+    Cocoa
+  ];
+
+  hardeningDisable = [ "format" ];
+
+  cmakeFlags = [
+    "-DLLDB_INCLUDE_TESTS=${if doCheck then "YES" else "NO"}"
+    "-DLLVM_ENABLE_RTTI=OFF"
+    "-DClang_DIR=${libclang.dev}/lib/cmake"
+    "-DLLVM_EXTERNAL_LIT=${lit}/bin/lit"
+  ] ++ lib.optionals stdenv.isDarwin [
+    "-DLLDB_USE_SYSTEM_DEBUGSERVER=ON"
+  ] ++ lib.optionals (!stdenv.isDarwin) [
+    "-DLLDB_CODESIGN_IDENTITY=" # codesigning makes nondeterministic
+  ] ++ lib.optionals enableManpages [
+    "-DLLVM_ENABLE_SPHINX=ON"
+    "-DSPHINX_OUTPUT_MAN=ON"
+    "-DSPHINX_OUTPUT_HTML=OFF"
+  ] ++ lib.optionals doCheck [
+    "-DLLDB_TEST_C_COMPILER=${stdenv.cc}/bin/${stdenv.cc.targetPrefix}cc"
+    "-DLLDB_TEST_CXX_COMPILER=${stdenv.cc}/bin/${stdenv.cc.targetPrefix}c++"
+  ];
+
+  doCheck = false;
+
+  postInstall = ''
+    # Editor support
+    # vscode:
+    install -D ../tools/lldb-vscode/package.json $out/share/vscode/extensions/llvm-org.lldb-vscode-0.1.0/package.json
+    mkdir -p $out/share/vscode/extensions/llvm-org.lldb-vscode-0.1.0/bin
+    ln -s $out/bin/lldb-vscode $out/share/vscode/extensions/llvm-org.lldb-vscode-0.1.0/bin
+  '';
+
+  meta = llvm_meta // {
+    homepage = "https://lldb.llvm.org/";
+    description = "A next-generation high-performance debugger";
+    longDescription = ''
+      LLDB is a next generation, high-performance debugger. It is built as a set
+      of reusable components which highly leverage existing libraries in the
+      larger LLVM Project, such as the Clang expression parser and LLVM
+      disassembler.
+    '';
+  };
+} // lib.optionalAttrs enableManpages {
+  pname = "lldb-manpages";
+
+  buildPhase = ''
+    make docs-lldb-man
+  '';
+
+  propagatedBuildInputs = [];
+
+  # manually install lldb man page
+  installPhase = ''
+    mkdir -p $out/share/man/man1
+    install docs/man/lldb.1 -t $out/share/man/man1/
+  '';
+
+  postPatch = null;
+  postInstall = null;
+
+  outputs = [ "out" ];
+
+  doCheck = false;
+
+  meta = llvm_meta // {
+    description = "man pages for LLDB ${version}";
+  };
+})
diff --git a/pkgs/development/compilers/llvm/git/lldb/gnu-install-dirs.patch b/pkgs/development/compilers/llvm/git/lldb/gnu-install-dirs.patch
new file mode 100644
index 000000000000..98321f4479e6
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/lldb/gnu-install-dirs.patch
@@ -0,0 +1,65 @@
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index b5633e21c56a..f2f1035e9238 100644
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -10,6 +10,8 @@ set(CMAKE_MODULE_PATH
+ # If we are not building as part of LLVM, build LLDB as a standalone project,
+ # using LLVM as an external library.
+ if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
++  include(GNUInstallDirs)
++
+   project(lldb)
+   include(LLDBStandalone)
+ 
+diff --git a/cmake/modules/AddLLDB.cmake b/cmake/modules/AddLLDB.cmake
+index 4ed5c647c5d2..89f96e710d55 100644
+--- a/cmake/modules/AddLLDB.cmake
++++ b/cmake/modules/AddLLDB.cmake
+@@ -107,13 +107,13 @@ function(add_lldb_library name)
+   endif()
+ 
+   if(PARAM_SHARED)
+-    set(install_dest lib${LLVM_LIBDIR_SUFFIX})
++    set(install_dest ${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX})
+     if(PARAM_INSTALL_PREFIX)
+       set(install_dest ${PARAM_INSTALL_PREFIX})
+     endif()
+     # RUNTIME is relevant for DLL platforms, FRAMEWORK for macOS
+     install(TARGETS ${name} COMPONENT ${name}
+-      RUNTIME DESTINATION bin
++      RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
+       LIBRARY DESTINATION ${install_dest}
+       ARCHIVE DESTINATION ${install_dest}
+       FRAMEWORK DESTINATION ${install_dest})
+diff --git a/cmake/modules/LLDBConfig.cmake b/cmake/modules/LLDBConfig.cmake
+index 2fdf1502d055..37364341ff8b 100644
+--- a/cmake/modules/LLDBConfig.cmake
++++ b/cmake/modules/LLDBConfig.cmake
+@@ -225,7 +225,7 @@ include_directories(BEFORE
+ if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
+   install(DIRECTORY include/
+     COMPONENT lldb-headers
+-    DESTINATION include
++    DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
+     FILES_MATCHING
+     PATTERN "*.h"
+     PATTERN ".cmake" EXCLUDE
+@@ -233,7 +233,7 @@ if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
+ 
+   install(DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/include/
+     COMPONENT lldb-headers
+-    DESTINATION include
++    DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
+     FILES_MATCHING
+     PATTERN "*.h"
+     PATTERN ".cmake" EXCLUDE
+diff --git a/tools/intel-features/CMakeLists.txt b/tools/intel-features/CMakeLists.txt
+index 734167e51bc5..f95761b5df58 100644
+--- a/tools/intel-features/CMakeLists.txt
++++ b/tools/intel-features/CMakeLists.txt
+@@ -65,4 +65,4 @@ if (LLDB_ENABLE_PYTHON AND LLDB_BUILD_INTEL_PT)
+ endif()
+ 
+ install(TARGETS lldbIntelFeatures
+-  LIBRARY DESTINATION lib${LLVM_LIBDIR_SUFFIX})
++  LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX})
diff --git a/pkgs/development/compilers/llvm/git/lldb/procfs.patch b/pkgs/development/compilers/llvm/git/lldb/procfs.patch
new file mode 100644
index 000000000000..b075dbaeee0a
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/lldb/procfs.patch
@@ -0,0 +1,31 @@
+--- a/source/Plugins/Process/Linux/Procfs.h
++++ b/source/Plugins/Process/Linux/Procfs.h
+@@ -11,21 +11,12 @@
+ // sys/procfs.h on Android/Linux for all supported architectures.
+ 
+ #include <sys/ptrace.h>
++#include <asm/ptrace.h>
+ 
+-#ifdef __ANDROID__
+-#if defined(__arm64__) || defined(__aarch64__)
+-typedef unsigned long elf_greg_t;
+-typedef elf_greg_t
+-    elf_gregset_t[(sizeof(struct user_pt_regs) / sizeof(elf_greg_t))];
+-typedef struct user_fpsimd_state elf_fpregset_t;
+-#ifndef NT_FPREGSET
+-#define NT_FPREGSET NT_PRFPREG
+-#endif // NT_FPREGSET
+-#elif defined(__mips__)
+-#ifndef NT_FPREGSET
+-#define NT_FPREGSET NT_PRFPREG
+-#endif // NT_FPREGSET
+-#endif
+-#else // __ANDROID__
++#if !defined(__GLIBC__) && defined(__powerpc__)
++#define pt_regs musl_pt_regs
++#include <sys/procfs.h>
++#undef pt_regs
++#else
+ #include <sys/procfs.h>
+-#endif // __ANDROID__
++#endif
diff --git a/pkgs/development/compilers/llvm/git/lldb/resource-dir.patch b/pkgs/development/compilers/llvm/git/lldb/resource-dir.patch
new file mode 100644
index 000000000000..e0db80afeb9f
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/lldb/resource-dir.patch
@@ -0,0 +1,13 @@
+diff --git a/lldb/cmake/modules/LLDBConfig.cmake b/lldb/cmake/modules/LLDBConfig.cmake
+index 37364341ff8b..7f74c1a3e257 100644
+--- a/cmake/modules/LLDBConfig.cmake
++++ b/cmake/modules/LLDBConfig.cmake
+@@ -257,7 +257,7 @@ if (NOT TARGET clang-resource-headers)
+   # Iterate over the possible places where the external resource directory
+   # could be and pick the first that exists.
+   foreach(CANDIDATE "${Clang_DIR}/../.." "${LLVM_DIR}" "${LLVM_LIBRARY_DIRS}"
+-                    "${LLVM_BUILD_LIBRARY_DIR}"
++                    "${LLVM_BUILD_LIBRARY_DIR}" "@clangLibDir@"
+                     "${LLVM_BINARY_DIR}/lib${LLVM_LIBDIR_SUFFIX}")
+     # Build the resource directory path by appending 'clang/<version number>'.
+     set(CANDIDATE_RESOURCE_DIR "${CANDIDATE}/clang/${LLDB_CLANG_RESOURCE_DIR_NAME}")
diff --git a/pkgs/development/compilers/llvm/git/llvm/default.nix b/pkgs/development/compilers/llvm/git/llvm/default.nix
new file mode 100644
index 000000000000..f65476a6fddd
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/llvm/default.nix
@@ -0,0 +1,220 @@
+{ lib, stdenv, llvm_meta
+, pkgsBuildBuild
+, src
+, fetchpatch
+, cmake
+, python3
+, libffi
+, libbfd
+, libpfm
+, libxml2
+, ncurses
+, version
+, release_version
+, zlib
+, buildLlvmTools
+, debugVersion ? false
+, enableManpages ? false
+, enableSharedLibraries ? !stdenv.hostPlatform.isStatic
+, enablePFM ? !(stdenv.isDarwin
+  || stdenv.isAarch64 # broken for Ampere eMAG 8180 (c2.large.arm on Packet) #56245
+  || stdenv.isAarch32 # broken for the armv7l builder
+)
+, enablePolly ? false
+}:
+
+let
+  inherit (lib) optional optionals optionalString;
+
+  # Used when creating a version-suffixed symlink of libLLVM.dylib
+  shortVersion = with lib;
+    concatStringsSep "." (take 1 (splitString "." release_version));
+
+in stdenv.mkDerivation (rec {
+  pname = "llvm";
+  inherit version;
+
+  inherit src;
+  sourceRoot = "source/${pname}";
+
+  outputs = [ "out" "lib" "dev" "python" ];
+
+  nativeBuildInputs = [ cmake python3 ]
+    ++ optionals enableManpages [ python3.pkgs.sphinx python3.pkgs.recommonmark ];
+
+  buildInputs = [ libxml2 libffi ]
+    ++ optional enablePFM libpfm; # exegesis
+
+  propagatedBuildInputs = [ ncurses zlib ];
+
+  patches = [
+    ./gnu-install-dirs.patch
+    # On older CPUs (e.g. Hydra/wendy) we'd be getting an error in this test.
+    (fetchpatch {
+      name = "uops-CMOV16rm-noreg.diff";
+      url = "https://github.com/llvm/llvm-project/commit/9e9f991ac033.diff";
+      sha256 = "sha256:12s8vr6ibri8b48h2z38f3afhwam10arfiqfy4yg37bmc054p5hi";
+      stripLen = 1;
+    })
+  ] ++ lib.optional enablePolly ./gnu-install-dirs-polly.patch;
+
+  postPatch = optionalString stdenv.isDarwin ''
+    substituteInPlace cmake/modules/AddLLVM.cmake \
+      --replace 'set(_install_name_dir INSTALL_NAME_DIR "@rpath")' "set(_install_name_dir)" \
+      --replace 'set(_install_rpath "@loader_path/../''${CMAKE_INSTALL_LIBDIR}''${LLVM_LIBDIR_SUFFIX}" ''${extra_libdir})' ""
+  ''
+  # Patch llvm-config to return correct library path based on --link-{shared,static}.
+  + optionalString (enableSharedLibraries) ''
+    substitute '${./outputs.patch}' ./outputs.patch --subst-var lib
+    patch -p1 < ./outputs.patch
+  '' + ''
+    # FileSystem permissions tests fail with various special bits
+    substituteInPlace unittests/Support/CMakeLists.txt \
+      --replace "Path.cpp" ""
+    rm unittests/Support/Path.cpp
+    substituteInPlace unittests/IR/CMakeLists.txt \
+      --replace "PassBuilderCallbacksTest.cpp" ""
+    rm unittests/IR/PassBuilderCallbacksTest.cpp
+  '' + optionalString stdenv.hostPlatform.isMusl ''
+    patch -p1 -i ${../../TLI-musl.patch}
+    substituteInPlace unittests/Support/CMakeLists.txt \
+      --replace "add_subdirectory(DynamicLibrary)" ""
+    rm unittests/Support/DynamicLibrary/DynamicLibraryTest.cpp
+    # valgrind unhappy with musl or glibc, but fails w/musl only
+    rm test/CodeGen/AArch64/wineh4.mir
+  '' + optionalString stdenv.hostPlatform.isAarch32 ''
+    # skip failing X86 test cases on 32-bit ARM
+    rm test/DebugInfo/X86/convert-debugloc.ll
+    rm test/DebugInfo/X86/convert-inlined.ll
+    rm test/DebugInfo/X86/convert-linked.ll
+    rm test/tools/dsymutil/X86/op-convert.test
+  '' + optionalString (stdenv.hostPlatform.system == "armv6l-linux") ''
+    # Seems to require certain floating point hardware (NEON?)
+    rm test/ExecutionEngine/frem.ll
+  '' + ''
+    patchShebangs test/BugPoint/compile-custom.ll.py
+  '';
+
+  # hacky fix: created binaries need to be run before installation
+  preBuild = ''
+    mkdir -p $out/
+    ln -sv $PWD/lib $out
+  '';
+
+  # E.g. mesa.drivers use the build-id as a cache key (see #93946):
+  LDFLAGS = optionalString (enableSharedLibraries && !stdenv.isDarwin) "-Wl,--build-id=sha1";
+
+  cmakeFlags = with stdenv; [
+    "-DLLVM_INSTALL_CMAKE_DIR=${placeholder "dev"}/lib/cmake/llvm/"
+    "-DCMAKE_BUILD_TYPE=${if debugVersion then "Debug" else "Release"}"
+    "-DLLVM_INSTALL_UTILS=ON"  # Needed by rustc
+    "-DLLVM_BUILD_TESTS=ON"
+    "-DLLVM_ENABLE_FFI=ON"
+    "-DLLVM_ENABLE_RTTI=ON"
+    "-DLLVM_HOST_TRIPLE=${stdenv.hostPlatform.config}"
+    "-DLLVM_DEFAULT_TARGET_TRIPLE=${stdenv.hostPlatform.config}"
+    "-DLLVM_ENABLE_DUMP=ON"
+  ] ++ optionals enableSharedLibraries [
+    "-DLLVM_LINK_LLVM_DYLIB=ON"
+  ] ++ optionals enableManpages [
+    "-DLLVM_BUILD_DOCS=ON"
+    "-DLLVM_ENABLE_SPHINX=ON"
+    "-DSPHINX_OUTPUT_MAN=ON"
+    "-DSPHINX_OUTPUT_HTML=OFF"
+    "-DSPHINX_WARNINGS_AS_ERRORS=OFF"
+  ] ++ optionals (!isDarwin) [
+    "-DLLVM_BINUTILS_INCDIR=${libbfd.dev}/include"
+  ] ++ optionals isDarwin [
+    "-DLLVM_ENABLE_LIBCXX=ON"
+    "-DCAN_TARGET_i386=false"
+  ] ++ optionals (stdenv.hostPlatform != stdenv.buildPlatform) [
+    "-DCMAKE_CROSSCOMPILING=True"
+    "-DLLVM_TABLEGEN=${buildLlvmTools.llvm}/bin/llvm-tblgen"
+    (
+      let
+        nativeCC = pkgsBuildBuild.targetPackages.stdenv.cc;
+        nativeBintools = nativeCC.bintools.bintools;
+        nativeToolchainFlags = [
+          "-DCMAKE_C_COMPILER=${nativeCC}/bin/${nativeCC.targetPrefix}cc"
+          "-DCMAKE_CXX_COMPILER=${nativeCC}/bin/${nativeCC.targetPrefix}c++"
+          "-DCMAKE_AR=${nativeBintools}/bin/${nativeBintools.targetPrefix}ar"
+          "-DCMAKE_STRIP=${nativeBintools}/bin/${nativeBintools.targetPrefix}strip"
+          "-DCMAKE_RANLIB=${nativeBintools}/bin/${nativeBintools.targetPrefix}ranlib"
+        ];
+      in "-DCROSS_TOOLCHAIN_FLAGS_NATIVE:list=${lib.concatStringsSep ";" nativeToolchainFlags}"
+    )
+  ];
+
+  postBuild = ''
+    rm -fR $out
+  '';
+
+  preCheck = ''
+    export LD_LIBRARY_PATH=$LD_LIBRARY_PATH''${LD_LIBRARY_PATH:+:}$PWD/lib
+  '';
+
+  postInstall = ''
+    mkdir -p $python/share
+    mv $out/share/opt-viewer $python/share/opt-viewer
+    moveToOutput "bin/llvm-config*" "$dev"
+    substituteInPlace "$dev/lib/cmake/llvm/LLVMExports-${if debugVersion then "debug" else "release"}.cmake" \
+      --replace "\''${_IMPORT_PREFIX}/lib/lib" "$lib/lib/lib" \
+      --replace "$out/bin/llvm-config" "$dev/bin/llvm-config"
+    substituteInPlace "$dev/lib/cmake/llvm/LLVMConfig.cmake" \
+      --replace 'set(LLVM_BINARY_DIR "''${LLVM_INSTALL_PREFIX}")' 'set(LLVM_BINARY_DIR "''${LLVM_INSTALL_PREFIX}'"$lib"'")'
+  ''
+  + optionalString (stdenv.isDarwin && enableSharedLibraries) ''
+    ln -s $lib/lib/libLLVM.dylib $lib/lib/libLLVM-${shortVersion}.dylib
+    ln -s $lib/lib/libLLVM.dylib $lib/lib/libLLVM-${release_version}.dylib
+  ''
+  + optionalString (stdenv.buildPlatform != stdenv.hostPlatform) ''
+    cp NATIVE/bin/llvm-config $dev/bin/llvm-config-native
+  '';
+
+  doCheck = stdenv.isLinux && (!stdenv.isx86_32) && (!stdenv.hostPlatform.isMusl);
+
+  checkTarget = "check-all";
+
+  requiredSystemFeatures = [ "big-parallel" ];
+  meta = llvm_meta // {
+    homepage = "https://llvm.org/";
+    description = "A collection of modular and reusable compiler and toolchain technologies";
+    longDescription = ''
+      The LLVM Project is a collection of modular and reusable compiler and
+      toolchain technologies. Despite its name, LLVM has little to do with
+      traditional virtual machines. The name "LLVM" itself is not an acronym; it
+      is the full name of the project.
+      LLVM began as a research project at the University of Illinois, with the
+      goal of providing a modern, SSA-based compilation strategy capable of
+      supporting both static and dynamic compilation of arbitrary programming
+      languages. Since then, LLVM has grown to be an umbrella project consisting
+      of a number of subprojects, many of which are being used in production by
+      a wide variety of commercial and open source projects as well as being
+      widely used in academic research. Code in the LLVM project is licensed
+      under the "Apache 2.0 License with LLVM exceptions".
+    '';
+  };
+} // lib.optionalAttrs enableManpages {
+  pname = "llvm-manpages";
+
+  buildPhase = ''
+    make docs-llvm-man
+  '';
+
+  propagatedBuildInputs = [];
+
+  installPhase = ''
+    make -C docs install
+  '';
+
+  postPatch = null;
+  postInstall = null;
+
+  outputs = [ "out" ];
+
+  doCheck = false;
+
+  meta = llvm_meta // {
+    description = "man pages for LLVM ${version}";
+  };
+})
diff --git a/pkgs/development/compilers/llvm/git/llvm/gnu-install-dirs-polly.patch b/pkgs/development/compilers/llvm/git/llvm/gnu-install-dirs-polly.patch
new file mode 100644
index 000000000000..68f3c45396f6
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/llvm/gnu-install-dirs-polly.patch
@@ -0,0 +1,105 @@
+diff --git a/tools/polly/CMakeLists.txt b/tools/polly/CMakeLists.txt
+index ca7c04c565bb..6ed5db5dd4f8 100644
+--- a/tools/polly/CMakeLists.txt
++++ b/tools/polly/CMakeLists.txt
+@@ -2,7 +2,11 @@
+ if (NOT DEFINED LLVM_MAIN_SRC_DIR)
+   project(Polly)
+   cmake_minimum_required(VERSION 3.13.4)
++endif()
++
++include(GNUInstallDirs)
+ 
++if (NOT DEFINED LLVM_MAIN_SRC_DIR)
+   # Where is LLVM installed?
+   find_package(LLVM CONFIG REQUIRED)
+   set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} ${LLVM_CMAKE_DIR})
+@@ -122,13 +126,13 @@ include_directories(
+ 
+ if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
+   install(DIRECTORY include/
+-    DESTINATION include
++    DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
+     FILES_MATCHING
+     PATTERN "*.h"
+     )
+ 
+   install(DIRECTORY ${POLLY_BINARY_DIR}/include/
+-    DESTINATION include
++    DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
+     FILES_MATCHING
+     PATTERN "*.h"
+     PATTERN "CMakeFiles" EXCLUDE
+diff --git a/tools/polly/cmake/CMakeLists.txt b/tools/polly/cmake/CMakeLists.txt
+index 7cc129ba2e90..137be25e4b80 100644
+--- a/tools/polly/cmake/CMakeLists.txt
++++ b/tools/polly/cmake/CMakeLists.txt
+@@ -79,18 +79,18 @@ file(GENERATE
+ 
+ # Generate PollyConfig.cmake for the install tree.
+ unset(POLLY_EXPORTS)
+-set(POLLY_INSTALL_PREFIX "${CMAKE_INSTALL_PREFIX}")
++set(POLLY_INSTALL_PREFIX "")
+ set(POLLY_CONFIG_LLVM_CMAKE_DIR "${LLVM_BINARY_DIR}/${LLVM_INSTALL_PACKAGE_DIR}")
+-set(POLLY_CONFIG_CMAKE_DIR "${POLLY_INSTALL_PREFIX}/${POLLY_INSTALL_PACKAGE_DIR}")
+-set(POLLY_CONFIG_LIBRARY_DIRS "${POLLY_INSTALL_PREFIX}/lib${LLVM_LIBDIR_SUFFIX}")
++set(POLLY_CONFIG_CMAKE_DIR "${POLLY_INSTALL_PREFIX}${CMAKE_INSTALL_PREFIX}/${POLLY_INSTALL_PACKAGE_DIR}")
++set(POLLY_CONFIG_LIBRARY_DIRS "${POLLY_INSTALL_PREFIX}${CMAKE_INSTALL_FULL_LIBDIR}${LLVM_LIBDIR_SUFFIX}")
+ if (POLLY_BUNDLED_ISL)
+   set(POLLY_CONFIG_INCLUDE_DIRS
+-    "${POLLY_INSTALL_PREFIX}/include"
+-    "${POLLY_INSTALL_PREFIX}/include/polly"
++    "${POLLY_INSTALL_PREFIX}${CMAKE_INSTALL_FULL_LIBDIR}"
++    "${POLLY_INSTALL_PREFIX}${CMAKE_INSTALL_FULL_LIBDIR}/polly"
+     )
+ else()
+   set(POLLY_CONFIG_INCLUDE_DIRS
+-    "${POLLY_INSTALL_PREFIX}/include"
++    "${POLLY_INSTALL_PREFIX}${CMAKE_INSTALL_FULL_INCLUDEDIR}"
+     ${ISL_INCLUDE_DIRS}
+     )
+ endif()
+@@ -100,12 +100,12 @@ endif()
+ foreach(tgt IN LISTS POLLY_CONFIG_EXPORTED_TARGETS)
+   get_target_property(tgt_type ${tgt} TYPE)
+   if (tgt_type STREQUAL "EXECUTABLE")
+-    set(tgt_prefix "bin/")
++    set(tgt_prefix "${CMAKE_INSTALL_BINDIR}/")
+   else()
+-    set(tgt_prefix "lib/")
++    set(tgt_prefix "${CMAKE_INSTALL_LIBDIR}/")
+   endif()
+ 
+-  set(tgt_path "${CMAKE_INSTALL_PREFIX}/${tgt_prefix}$<TARGET_FILE_NAME:${tgt}>")
++  set(tgt_path "${tgt_prefix}$<TARGET_FILE_NAME:${tgt}>")
+   file(RELATIVE_PATH tgt_path ${POLLY_CONFIG_CMAKE_DIR} ${tgt_path})
+ 
+   if (NOT tgt_type STREQUAL "INTERFACE_LIBRARY")
+diff --git a/tools/polly/cmake/polly_macros.cmake b/tools/polly/cmake/polly_macros.cmake
+index 518a09b45a42..bd9d6f5542ad 100644
+--- a/tools/polly/cmake/polly_macros.cmake
++++ b/tools/polly/cmake/polly_macros.cmake
+@@ -44,8 +44,8 @@ macro(add_polly_library name)
+   if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY OR ${name} STREQUAL "LLVMPolly")
+     install(TARGETS ${name}
+       EXPORT LLVMExports
+-      LIBRARY DESTINATION lib${LLVM_LIBDIR_SUFFIX}
+-      ARCHIVE DESTINATION lib${LLVM_LIBDIR_SUFFIX})
++	  LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}
++      ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX})
+   endif()
+   set_property(GLOBAL APPEND PROPERTY LLVM_EXPORTS ${name})
+ endmacro(add_polly_library)
+diff --git a/tools/polly/lib/External/CMakeLists.txt b/tools/polly/lib/External/CMakeLists.txt
+index 8991094d92c7..178d8ad606bb 100644
+--- a/tools/polly/lib/External/CMakeLists.txt
++++ b/tools/polly/lib/External/CMakeLists.txt
+@@ -275,7 +275,7 @@ if (POLLY_BUNDLED_ISL)
+     install(DIRECTORY
+       ${ISL_SOURCE_DIR}/include/
+       ${ISL_BINARY_DIR}/include/
+-      DESTINATION include/polly
++      DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/polly
+       FILES_MATCHING
+       PATTERN "*.h"
+       PATTERN "CMakeFiles" EXCLUDE
diff --git a/pkgs/development/compilers/llvm/git/llvm/gnu-install-dirs.patch b/pkgs/development/compilers/llvm/git/llvm/gnu-install-dirs.patch
new file mode 100644
index 000000000000..da8dc1445171
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/llvm/gnu-install-dirs.patch
@@ -0,0 +1,417 @@
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index 277d0fe54d7b..af69c8be8745 100644
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -256,15 +256,21 @@ if (CMAKE_BUILD_TYPE AND
+   message(FATAL_ERROR "Invalid value for CMAKE_BUILD_TYPE: ${CMAKE_BUILD_TYPE}")
+ endif()
+ 
++include(GNUInstallDirs)
++
+ set(LLVM_LIBDIR_SUFFIX "" CACHE STRING "Define suffix of library directory name (32/64)" )
+ 
+-set(LLVM_TOOLS_INSTALL_DIR "bin" CACHE STRING "Path for binary subdirectory (defaults to 'bin')")
++set(LLVM_TOOLS_INSTALL_DIR "${CMAKE_INSTALL_BINDIR}" CACHE STRING
++    "Path for binary subdirectory (defaults to 'bin')")
+ mark_as_advanced(LLVM_TOOLS_INSTALL_DIR)
+ 
+ set(LLVM_UTILS_INSTALL_DIR "${LLVM_TOOLS_INSTALL_DIR}" CACHE STRING
+     "Path to install LLVM utilities (enabled by LLVM_INSTALL_UTILS=ON) (defaults to LLVM_TOOLS_INSTALL_DIR)")
+ mark_as_advanced(LLVM_UTILS_INSTALL_DIR)
+ 
++set(LLVM_INSTALL_CMAKE_DIR "${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}/cmake/llvm" CACHE STRING
++	"Path for CMake subdirectory (defaults to lib/cmake/llvm)" )
++
+ # They are used as destination of target generators.
+ set(LLVM_RUNTIME_OUTPUT_INTDIR ${CMAKE_CURRENT_BINARY_DIR}/${CMAKE_CFG_INTDIR}/bin)
+ set(LLVM_LIBRARY_OUTPUT_INTDIR ${CMAKE_CURRENT_BINARY_DIR}/${CMAKE_CFG_INTDIR}/lib${LLVM_LIBDIR_SUFFIX})
+@@ -567,9 +573,9 @@ option (LLVM_ENABLE_SPHINX "Use Sphinx to generate llvm documentation." OFF)
+ option (LLVM_ENABLE_OCAMLDOC "Build OCaml bindings documentation." ON)
+ option (LLVM_ENABLE_BINDINGS "Build bindings." ON)
+ 
+-set(LLVM_INSTALL_DOXYGEN_HTML_DIR "share/doc/llvm/doxygen-html"
++set(LLVM_INSTALL_DOXYGEN_HTML_DIR "${CMAKE_INSTALL_DOCDIR}/${project}/doxygen-html"
+     CACHE STRING "Doxygen-generated HTML documentation install directory")
+-set(LLVM_INSTALL_OCAMLDOC_HTML_DIR "share/doc/llvm/ocaml-html"
++set(LLVM_INSTALL_OCAMLDOC_HTML_DIR "${CMAKE_INSTALL_DOCDIR}/${project}/ocaml-html"
+     CACHE STRING "OCamldoc-generated HTML documentation install directory")
+ 
+ option (LLVM_BUILD_EXTERNAL_COMPILER_RT
+@@ -1027,7 +1033,7 @@ endif()
+ 
+ if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
+   install(DIRECTORY include/llvm include/llvm-c
+-    DESTINATION include
++    DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
+     COMPONENT llvm-headers
+     FILES_MATCHING
+     PATTERN "*.def"
+@@ -1038,7 +1044,7 @@ if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
+     )
+ 
+   install(DIRECTORY ${LLVM_INCLUDE_DIR}/llvm ${LLVM_INCLUDE_DIR}/llvm-c
+-    DESTINATION include
++    DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
+     COMPONENT llvm-headers
+     FILES_MATCHING
+     PATTERN "*.def"
+@@ -1052,13 +1058,13 @@ if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
+ 
+   if (LLVM_INSTALL_MODULEMAPS)
+     install(DIRECTORY include/llvm include/llvm-c
+-            DESTINATION include
++            DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
+             COMPONENT llvm-headers
+             FILES_MATCHING
+             PATTERN "module.modulemap"
+             )
+     install(FILES include/llvm/module.install.modulemap
+-            DESTINATION include/llvm
++            DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/llvm
+             COMPONENT llvm-headers
+             RENAME "module.extern.modulemap"
+             )
+diff --git a/cmake/modules/AddLLVM.cmake b/cmake/modules/AddLLVM.cmake
+index 97c9980c7de3..409e8b615f75 100644
+--- a/cmake/modules/AddLLVM.cmake
++++ b/cmake/modules/AddLLVM.cmake
+@@ -804,9 +804,9 @@ macro(add_llvm_library name)
+ 
+       install(TARGETS ${name}
+               ${export_to_llvmexports}
+-              LIBRARY DESTINATION lib${LLVM_LIBDIR_SUFFIX} COMPONENT ${name}
+-              ARCHIVE DESTINATION lib${LLVM_LIBDIR_SUFFIX} COMPONENT ${name}
+-              RUNTIME DESTINATION bin COMPONENT ${name})
++              LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX} COMPONENT ${name}
++              ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX} COMPONENT ${name}
++              RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR} COMPONENT ${name})
+ 
+       if (NOT LLVM_ENABLE_IDE)
+         add_llvm_install_targets(install-${name}
+@@ -1022,7 +1022,7 @@ function(process_llvm_pass_plugins)
+           "set(LLVM_STATIC_EXTENSIONS ${LLVM_STATIC_EXTENSIONS})")
+       install(FILES
+           ${llvm_cmake_builddir}/LLVMConfigExtensions.cmake
+-          DESTINATION ${LLVM_INSTALL_PACKAGE_DIR}
++          DESTINATION ${LLVM_INSTALL_CMAKE_DIR}
+           COMPONENT cmake-exports)
+ 
+       set(ExtensionDef "${LLVM_BINARY_DIR}/include/llvm/Support/Extension.def")
+@@ -1242,7 +1242,7 @@ macro(add_llvm_example name)
+   endif()
+   add_llvm_executable(${name} ${ARGN})
+   if( LLVM_BUILD_EXAMPLES )
+-    install(TARGETS ${name} RUNTIME DESTINATION examples)
++    install(TARGETS ${name} RUNTIME DESTINATION ${CMAKE_INSTALL_DOCDIR}/examples)
+   endif()
+   set_target_properties(${name} PROPERTIES FOLDER "Examples")
+ endmacro(add_llvm_example name)
+@@ -1854,7 +1854,7 @@ function(llvm_install_library_symlink name dest type)
+   set(full_name ${CMAKE_${type}_LIBRARY_PREFIX}${name}${CMAKE_${type}_LIBRARY_SUFFIX})
+   set(full_dest ${CMAKE_${type}_LIBRARY_PREFIX}${dest}${CMAKE_${type}_LIBRARY_SUFFIX})
+ 
+-  set(output_dir lib${LLVM_LIBDIR_SUFFIX})
++  set(output_dir ${CMAKE_INSTALL_FULL_LIBDIR}${LLVM_LIBDIR_SUFFIX})
+   if(WIN32 AND "${type}" STREQUAL "SHARED")
+     set(output_dir bin)
+   endif()
+@@ -1871,7 +1871,7 @@ function(llvm_install_library_symlink name dest type)
+   endif()
+ endfunction()
+ 
+-function(llvm_install_symlink name dest)
++function(llvm_install_symlink name dest output_dir)
+   cmake_parse_arguments(ARG "ALWAYS_GENERATE" "COMPONENT" "" ${ARGN})
+   foreach(path ${CMAKE_MODULE_PATH})
+     if(EXISTS ${path}/LLVMInstallSymlink.cmake)
+@@ -1894,7 +1894,7 @@ function(llvm_install_symlink name dest)
+   set(full_dest ${dest}${CMAKE_EXECUTABLE_SUFFIX})
+ 
+   install(SCRIPT ${INSTALL_SYMLINK}
+-          CODE "install_symlink(${full_name} ${full_dest} ${LLVM_TOOLS_INSTALL_DIR})"
++          CODE "install_symlink(${full_name} ${full_dest} ${output_dir})"
+           COMPONENT ${component})
+ 
+   if (NOT LLVM_ENABLE_IDE AND NOT ARG_ALWAYS_GENERATE)
+@@ -1977,7 +1977,8 @@ function(add_llvm_tool_symlink link_name target)
+     endif()
+ 
+     if ((TOOL_IS_TOOLCHAIN OR NOT LLVM_INSTALL_TOOLCHAIN_ONLY) AND LLVM_BUILD_TOOLS)
+-      llvm_install_symlink(${link_name} ${target})
++      GNUInstallDirs_get_absolute_install_dir(output_dir LLVM_TOOLS_INSTALL_DIR)
++      llvm_install_symlink(${link_name} ${target} ${output_dir})
+     endif()
+   endif()
+ endfunction()
+@@ -2100,9 +2101,9 @@ function(llvm_setup_rpath name)
+ 
+   if (APPLE)
+     set(_install_name_dir INSTALL_NAME_DIR "@rpath")
+-    set(_install_rpath "@loader_path/../lib${LLVM_LIBDIR_SUFFIX}" ${extra_libdir})
++    set(_install_rpath "@loader_path/../${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}" ${extra_libdir})
+   elseif(UNIX)
+-    set(_install_rpath "\$ORIGIN/../lib${LLVM_LIBDIR_SUFFIX}" ${extra_libdir})
++    set(_install_rpath "\$ORIGIN/../${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}" ${extra_libdir})
+     if(${CMAKE_SYSTEM_NAME} MATCHES "(FreeBSD|DragonFly)")
+       set_property(TARGET ${name} APPEND_STRING PROPERTY
+                    LINK_FLAGS " -Wl,-z,origin ")
+diff --git a/cmake/modules/AddOCaml.cmake b/cmake/modules/AddOCaml.cmake
+index 554046b20edf..4d1ad980641e 100644
+--- a/cmake/modules/AddOCaml.cmake
++++ b/cmake/modules/AddOCaml.cmake
+@@ -144,9 +144,9 @@ function(add_ocaml_library name)
+   endforeach()
+ 
+   if( APPLE )
+-    set(ocaml_rpath "@executable_path/../../../lib${LLVM_LIBDIR_SUFFIX}")
++    set(ocaml_rpath "@executable_path/../../../${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}")
+   elseif( UNIX )
+-    set(ocaml_rpath "\\$ORIGIN/../../../lib${LLVM_LIBDIR_SUFFIX}")
++    set(ocaml_rpath "\\$ORIGIN/../../../${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}")
+   endif()
+   list(APPEND ocaml_flags "-ldopt" "-Wl,-rpath,${ocaml_rpath}")
+ 
+diff --git a/cmake/modules/AddSphinxTarget.cmake b/cmake/modules/AddSphinxTarget.cmake
+index e80c3b5c1cac..482f6d715ef5 100644
+--- a/cmake/modules/AddSphinxTarget.cmake
++++ b/cmake/modules/AddSphinxTarget.cmake
+@@ -90,7 +90,7 @@ function (add_sphinx_target builder project)
+         endif()
+       elseif (builder STREQUAL html)
+         string(TOUPPER "${project}" project_upper)
+-        set(${project_upper}_INSTALL_SPHINX_HTML_DIR "share/doc/${project}/html"
++        set(${project_upper}_INSTALL_SPHINX_HTML_DIR "${CMAKE_INSTALL_DOCDIR}/${project}/html"
+             CACHE STRING "HTML documentation install directory for ${project}")
+ 
+         # '/.' indicates: copy the contents of the directory directly into
+diff --git a/cmake/modules/CMakeLists.txt b/cmake/modules/CMakeLists.txt
+index 505dc9a29d70..36e6c63af3f4 100644
+--- a/cmake/modules/CMakeLists.txt
++++ b/cmake/modules/CMakeLists.txt
+@@ -1,4 +1,4 @@
+-set(LLVM_INSTALL_PACKAGE_DIR lib${LLVM_LIBDIR_SUFFIX}/cmake/llvm)
++set(LLVM_INSTALL_PACKAGE_DIR ${LLVM_INSTALL_CMAKE_DIR} CACHE STRING "Path for CMake subdirectory (defaults to 'cmake/llvm')")
+ set(llvm_cmake_builddir "${LLVM_BINARY_DIR}/${LLVM_INSTALL_PACKAGE_DIR}")
+ 
+ # First for users who use an installed LLVM, create the LLVMExports.cmake file.
+@@ -107,13 +107,13 @@ foreach(p ${_count})
+   set(LLVM_CONFIG_CODE "${LLVM_CONFIG_CODE}
+ get_filename_component(LLVM_INSTALL_PREFIX \"\${LLVM_INSTALL_PREFIX}\" PATH)")
+ endforeach(p)
+-set(LLVM_CONFIG_INCLUDE_DIRS "\${LLVM_INSTALL_PREFIX}/include")
++set(LLVM_CONFIG_INCLUDE_DIRS "\${LLVM_INSTALL_PREFIX}/${CMAKE_INSTALL_INCLUDEDIR}")
+ set(LLVM_CONFIG_INCLUDE_DIR "${LLVM_CONFIG_INCLUDE_DIRS}")
+ set(LLVM_CONFIG_MAIN_INCLUDE_DIR "${LLVM_CONFIG_INCLUDE_DIRS}")
+-set(LLVM_CONFIG_LIBRARY_DIRS "\${LLVM_INSTALL_PREFIX}/lib\${LLVM_LIBDIR_SUFFIX}")
++set(LLVM_CONFIG_LIBRARY_DIRS "\${LLVM_INSTALL_PREFIX}/${CMAKE_INSTALL_LIBDIR}\${LLVM_LIBDIR_SUFFIX}")
+ set(LLVM_CONFIG_CMAKE_DIR "\${LLVM_INSTALL_PREFIX}/${LLVM_INSTALL_PACKAGE_DIR}")
+ set(LLVM_CONFIG_BINARY_DIR "\${LLVM_INSTALL_PREFIX}")
+-set(LLVM_CONFIG_TOOLS_BINARY_DIR "\${LLVM_INSTALL_PREFIX}/bin")
++set(LLVM_CONFIG_TOOLS_BINARY_DIR "\${LLVM_INSTALL_PREFIX}/${CMAKE_INSTALL_BINDIR}")
+ 
+ # Generate a default location for lit
+ if (LLVM_INSTALL_UTILS AND LLVM_BUILD_UTILS)
+diff --git a/cmake/modules/LLVMInstallSymlink.cmake b/cmake/modules/LLVMInstallSymlink.cmake
+index 09fed8085c23..aa79f192abf0 100644
+--- a/cmake/modules/LLVMInstallSymlink.cmake
++++ b/cmake/modules/LLVMInstallSymlink.cmake
+@@ -10,7 +10,7 @@ function(install_symlink name target outdir)
+     set(LINK_OR_COPY copy)
+   endif()
+ 
+-  set(bindir "${DESTDIR}${CMAKE_INSTALL_PREFIX}/${outdir}/")
++  set(bindir "${DESTDIR}${outdir}/")
+ 
+   message(STATUS "Creating ${name}")
+ 
+diff --git a/docs/CMake.rst b/docs/CMake.rst
+index bb821b417ad9..6a528f7c2ad3 100644
+--- a/docs/CMake.rst
++++ b/docs/CMake.rst
+@@ -196,7 +196,7 @@ CMake manual, or execute ``cmake --help-variable VARIABLE_NAME``.
+ **LLVM_LIBDIR_SUFFIX**:STRING
+   Extra suffix to append to the directory where libraries are to be
+   installed. On a 64-bit architecture, one could use ``-DLLVM_LIBDIR_SUFFIX=64``
+-  to install libraries to ``/usr/lib64``.
++  to install libraries to ``/usr/lib64``. See also ``CMAKE_INSTALL_LIBDIR``.
+ 
+ **CMAKE_C_FLAGS**:STRING
+   Extra flags to use when compiling C source files.
+@@ -550,8 +550,8 @@ LLVM-specific variables
+ 
+ **LLVM_INSTALL_DOXYGEN_HTML_DIR**:STRING
+   The path to install Doxygen-generated HTML documentation to. This path can
+-  either be absolute or relative to the CMAKE_INSTALL_PREFIX. Defaults to
+-  `share/doc/llvm/doxygen-html`.
++  either be absolute or relative to the ``CMAKE_INSTALL_PREFIX``. Defaults to
++  `${CMAKE_INSTALL_DOCDIR}/${project}/doxygen-html`.
+ 
+ **LLVM_ENABLE_SPHINX**:BOOL
+   If specified, CMake will search for the ``sphinx-build`` executable and will make
+@@ -582,13 +582,33 @@ LLVM-specific variables
+ 
+ **LLVM_INSTALL_SPHINX_HTML_DIR**:STRING
+   The path to install Sphinx-generated HTML documentation to. This path can
+-  either be absolute or relative to the CMAKE_INSTALL_PREFIX. Defaults to
+-  `share/doc/llvm/html`.
++  either be absolute or relative to the ``CMAKE_INSTALL_PREFIX``. Defaults to
++  `${CMAKE_INSTALL_DOCDIR}/${project}/html`.
+ 
+ **LLVM_INSTALL_OCAMLDOC_HTML_DIR**:STRING
+   The path to install OCamldoc-generated HTML documentation to. This path can
+-  either be absolute or relative to the CMAKE_INSTALL_PREFIX. Defaults to
+-  `share/doc/llvm/ocaml-html`.
++  either be absolute or relative to the ``CMAKE_INSTALL_PREFIX``. Defaults to
++  `${CMAKE_INSTALL_DOCDIR}/${project}/ocaml-html`.
++
++**CMAKE_INSTALL_BINDIR**:STRING
++  The path to install binary tools, relative to the ``CMAKE_INSTALL_PREFIX``.
++  Defaults to `bin`.
++
++**CMAKE_INSTALL_LIBDIR**:STRING
++  The path to install libraries, relative to the ``CMAKE_INSTALL_PREFIX``.
++  Defaults to `lib`.
++
++**CMAKE_INSTALL_INCLUDEDIR**:STRING
++  The path to install header files, relative to the ``CMAKE_INSTALL_PREFIX``.
++  Defaults to `include`.
++
++**CMAKE_INSTALL_DOCDIR**:STRING
++  The path to install documentation, relative to the ``CMAKE_INSTALL_PREFIX``.
++  Defaults to `share/doc`.
++
++**CMAKE_INSTALL_MANDIR**:STRING
++  The path to install manpage files, relative to the ``CMAKE_INSTALL_PREFIX``.
++  Defaults to `share/man`.
+ 
+ **LLVM_CREATE_XCODE_TOOLCHAIN**:BOOL
+   macOS Only: If enabled CMake will generate a target named
+@@ -786,9 +806,11 @@ the ``cmake`` command or by setting it directly in ``ccmake`` or ``cmake-gui``).
+ 
+ This file is available in two different locations.
+ 
+-* ``<INSTALL_PREFIX>/lib/cmake/llvm/LLVMConfig.cmake`` where
+-  ``<INSTALL_PREFIX>`` is the install prefix of an installed version of LLVM.
+-  On Linux typically this is ``/usr/lib/cmake/llvm/LLVMConfig.cmake``.
++* ``<LLVM_INSTALL_PACKAGE_DIR>LLVMConfig.cmake`` where
++  ``<LLVM_INSTALL_PACKAGE_DIR>`` is the location where LLVM CMake modules are
++  installed as part of an installed version of LLVM. This is typically
++  ``cmake/llvm/`` within the lib directory. On Linux, this is typically
++  ``/usr/lib/cmake/llvm/LLVMConfig.cmake``.
+ 
+ * ``<LLVM_BUILD_ROOT>/lib/cmake/llvm/LLVMConfig.cmake`` where
+   ``<LLVM_BUILD_ROOT>`` is the root of the LLVM build tree. **Note: this is only
+diff --git a/examples/Bye/CMakeLists.txt b/examples/Bye/CMakeLists.txt
+index bb96edb4b4bf..678c22fb43c8 100644
+--- a/examples/Bye/CMakeLists.txt
++++ b/examples/Bye/CMakeLists.txt
+@@ -14,6 +14,6 @@ if (NOT WIN32)
+     BUILDTREE_ONLY
+    )
+ 
+-  install(TARGETS ${name} RUNTIME DESTINATION examples)
++  install(TARGETS ${name} RUNTIME DESTINATION ${CMAKE_INSTALL_DOCDIR}/examples)
+   set_target_properties(${name} PROPERTIES FOLDER "Examples")
+ endif()
+diff --git a/include/llvm/CMakeLists.txt b/include/llvm/CMakeLists.txt
+index b46319f24fc8..2feabd1954e4 100644
+--- a/include/llvm/CMakeLists.txt
++++ b/include/llvm/CMakeLists.txt
+@@ -5,5 +5,5 @@ add_subdirectory(Frontend)
+ # If we're doing an out-of-tree build, copy a module map for generated
+ # header files into the build area.
+ if (NOT "${CMAKE_SOURCE_DIR}" STREQUAL "${CMAKE_BINARY_DIR}")
+-  configure_file(module.modulemap.build module.modulemap COPYONLY)
++  configure_file(module.modulemap.build ${LLVM_INCLUDE_DIR}/module.modulemap COPYONLY)
+ endif (NOT "${CMAKE_SOURCE_DIR}" STREQUAL "${CMAKE_BINARY_DIR}")
+diff --git a/tools/llvm-config/BuildVariables.inc.in b/tools/llvm-config/BuildVariables.inc.in
+index ebe5b73a5c65..70c497be12f5 100644
+--- a/tools/llvm-config/BuildVariables.inc.in
++++ b/tools/llvm-config/BuildVariables.inc.in
+@@ -23,6 +23,10 @@
+ #define LLVM_CXXFLAGS "@LLVM_CXXFLAGS@"
+ #define LLVM_BUILDMODE "@LLVM_BUILDMODE@"
+ #define LLVM_LIBDIR_SUFFIX "@LLVM_LIBDIR_SUFFIX@"
++#define LLVM_INSTALL_BINDIR "@CMAKE_INSTALL_BINDIR@"
++#define LLVM_INSTALL_LIBDIR "@CMAKE_INSTALL_LIBDIR@"
++#define LLVM_INSTALL_INCLUDEDIR "@CMAKE_INSTALL_INCLUDEDIR@"
++#define LLVM_INSTALL_CMAKEDIR "@LLVM_INSTALL_CMAKE_DIR@"
+ #define LLVM_TARGETS_BUILT "@LLVM_TARGETS_BUILT@"
+ #define LLVM_SYSTEM_LIBS "@LLVM_SYSTEM_LIBS@"
+ #define LLVM_BUILD_SYSTEM "@LLVM_BUILD_SYSTEM@"
+diff --git a/tools/llvm-config/llvm-config.cpp b/tools/llvm-config/llvm-config.cpp
+index 1a2f04552d13..44fa7d3eec6b 100644
+--- a/tools/llvm-config/llvm-config.cpp
++++ b/tools/llvm-config/llvm-config.cpp
+@@ -357,12 +357,26 @@ int main(int argc, char **argv) {
+         ("-I" + ActiveIncludeDir + " " + "-I" + ActiveObjRoot + "/include");
+   } else {
+     ActivePrefix = CurrentExecPrefix;
+-    ActiveIncludeDir = ActivePrefix + "/include";
+-    SmallString<256> path(StringRef(LLVM_TOOLS_INSTALL_DIR));
+-    sys::fs::make_absolute(ActivePrefix, path);
+-    ActiveBinDir = std::string(path.str());
+-    ActiveLibDir = ActivePrefix + "/lib" + LLVM_LIBDIR_SUFFIX;
+-    ActiveCMakeDir = ActiveLibDir + "/cmake/llvm";
++    {
++      SmallString<256> path(StringRef(LLVM_INSTALL_INCLUDEDIR));
++      sys::fs::make_absolute(ActivePrefix, path);
++      ActiveIncludeDir = std::string(path.str());
++    }
++    {
++      SmallString<256> path(StringRef(LLVM_INSTALL_BINDIR));
++      sys::fs::make_absolute(ActivePrefix, path);
++      ActiveBinDir = std::string(path.str());
++    }
++    {
++      SmallString<256> path(StringRef(LLVM_INSTALL_LIBDIR LLVM_LIBDIR_SUFFIX));
++      sys::fs::make_absolute(ActivePrefix, path);
++      ActiveLibDir = std::string(path.str());
++    }
++    {
++      SmallString<256> path(StringRef(LLVM_INSTALL_CMAKEDIR));
++      sys::fs::make_absolute(ActivePrefix, path);
++      ActiveCMakeDir = std::string(path.str());
++    }
+     ActiveIncludeOption = "-I" + ActiveIncludeDir;
+   }
+ 
+diff --git a/tools/lto/CMakeLists.txt b/tools/lto/CMakeLists.txt
+index 2963f97cad88..69d66c9c9ca1 100644
+--- a/tools/lto/CMakeLists.txt
++++ b/tools/lto/CMakeLists.txt
+@@ -25,7 +25,7 @@ add_llvm_library(LTO SHARED INSTALL_WITH_TOOLCHAIN ${SOURCES} DEPENDS
+     intrinsics_gen)
+ 
+ install(FILES ${LLVM_MAIN_INCLUDE_DIR}/llvm-c/lto.h
+-  DESTINATION include/llvm-c
++  DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/llvm-c
+   COMPONENT LTO)
+ 
+ if (APPLE)
+diff --git a/tools/opt-viewer/CMakeLists.txt b/tools/opt-viewer/CMakeLists.txt
+index ead73ec13a8f..250362021f17 100644
+--- a/tools/opt-viewer/CMakeLists.txt
++++ b/tools/opt-viewer/CMakeLists.txt
+@@ -8,7 +8,7 @@ set (files
+ 
+ foreach (file ${files})
+   install(PROGRAMS ${file}
+-    DESTINATION share/opt-viewer
++    DESTINATION ${CMAKE_INSTALL_DATADIR}/opt-viewer
+     COMPONENT opt-viewer)
+ endforeach (file)
+ 
+diff --git a/tools/remarks-shlib/CMakeLists.txt b/tools/remarks-shlib/CMakeLists.txt
+index 865436247270..ce1daa62f6ab 100644
+--- a/tools/remarks-shlib/CMakeLists.txt
++++ b/tools/remarks-shlib/CMakeLists.txt
+@@ -19,7 +19,7 @@ if(LLVM_ENABLE_PIC)
+   endif()
+   
+   install(FILES ${LLVM_MAIN_INCLUDE_DIR}/llvm-c/Remarks.h
+-    DESTINATION include/llvm-c
++    DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/llvm-c
+     COMPONENT Remarks)
+ 
+   if (APPLE)
diff --git a/pkgs/development/compilers/llvm/git/llvm/outputs.patch b/pkgs/development/compilers/llvm/git/llvm/outputs.patch
new file mode 100644
index 000000000000..40096fa3497f
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/llvm/outputs.patch
@@ -0,0 +1,26 @@
+diff --git a/tools/llvm-config/llvm-config.cpp b/tools/llvm-config/llvm-config.cpp
+index 94d426b..37f7794 100644
+--- a/tools/llvm-config/llvm-config.cpp
++++ b/tools/llvm-config/llvm-config.cpp
+@@ -333,6 +333,21 @@ int main(int argc, char **argv) {
+     ActiveIncludeOption = "-I" + ActiveIncludeDir;
+   }
+ 
++  /// Nix-specific multiple-output handling: override ActiveLibDir if --link-shared
++  if (!IsInDevelopmentTree) {
++    bool WantShared = true;
++    for (int i = 1; i < argc; ++i) {
++      StringRef Arg = argv[i];
++      if (Arg == "--link-shared")
++        WantShared = true;
++      else if (Arg == "--link-static")
++        WantShared = false; // the last one wins
++    }
++
++    if (WantShared)
++      ActiveLibDir = std::string("@lib@") + "/lib" + LLVM_LIBDIR_SUFFIX;
++  }
++
+   /// We only use `shared library` mode in cases where the static library form
+   /// of the components provided are not available; note however that this is
+   /// skipped if we're run from within the build dir. However, once installed,
diff --git a/pkgs/development/compilers/llvm/git/openmp/default.nix b/pkgs/development/compilers/llvm/git/openmp/default.nix
new file mode 100644
index 000000000000..07488c1c33f4
--- /dev/null
+++ b/pkgs/development/compilers/llvm/git/openmp/default.nix
@@ -0,0 +1,35 @@
+{ lib
+, stdenv
+, llvm_meta
+, src
+, cmake
+, llvm
+, perl
+, version
+}:
+
+stdenv.mkDerivation rec {
+  pname = "openmp";
+  inherit version;
+
+  inherit src;
+  sourceRoot = "source/${pname}";
+
+  nativeBuildInputs = [ cmake perl ];
+  buildInputs = [ llvm ];
+
+  meta = llvm_meta // {
+    homepage = "https://openmp.llvm.org/";
+    description = "Support for the OpenMP language";
+    longDescription = ''
+      The OpenMP subproject of LLVM contains the components required to build an
+      executable OpenMP program that are outside the compiler itself.
+      Contains the code for the runtime library against which code compiled by
+      "clang -fopenmp" must be linked before it can run and the library that
+      supports offload to target devices.
+    '';
+    # "All of the code is dual licensed under the MIT license and the UIUC
+    # License (a BSD-like license)":
+    license = with lib.licenses; [ mit ncsa ];
+  };
+}
diff --git a/pkgs/top-level/aliases.nix b/pkgs/top-level/aliases.nix
index 351e3025dede..4429742fbe6b 100644
--- a/pkgs/top-level/aliases.nix
+++ b/pkgs/top-level/aliases.nix
@@ -1072,4 +1072,11 @@ mapAliases ({
     sddm
   ;
 
+  # LLVM packages for (integration) testing that should not be used inside Nixpkgs:
+  llvmPackages_git = recurseIntoAttrs (callPackage ../development/compilers/llvm/git {
+    inherit (stdenvAdapters) overrideCC;
+    buildLlvmTools = buildPackages.llvmPackages_git.tools;
+    targetLlvmLibraries = targetPackages.llvmPackages_git.libraries;
+  });
+
 })