diff --git a/pkgs/development/compilers/llvm/6/clang/default.nix b/pkgs/development/compilers/llvm/6/clang/default.nix
index b1f2ba27e8c8..6707ebd5413b 100644
--- a/pkgs/development/compilers/llvm/6/clang/default.nix
+++ b/pkgs/development/compilers/llvm/6/clang/default.nix
@@ -9,7 +9,7 @@ let
     name = "clang-${version}";
 
     unpackPhase = ''
-      unpackFile ${fetch "cfe" "1j9pzl71r1bnp0dsxj33p5pvl6njg0bf2yyi9vhci13nw7y71i0x"}
+      unpackFile ${fetch "cfe" "1nxx253czzjy7bsrwvk2pyaxwiqwqkjzk0k8x8w7y19mzmmfz883"}
       mv cfe-${version}* clang
       sourceRoot=$PWD/clang
       unpackFile ${clang-tools-extra_src}
diff --git a/pkgs/development/compilers/llvm/6/default.nix b/pkgs/development/compilers/llvm/6/default.nix
index c49f9e3d7340..8d9fdfc26201 100644
--- a/pkgs/development/compilers/llvm/6/default.nix
+++ b/pkgs/development/compilers/llvm/6/default.nix
@@ -7,15 +7,15 @@ let
   callPackage = newScope (self // { inherit stdenv cmake libxml2 python2 isl release_version version fetch; });
 
   release_version = "6.0.0";
-  version = "6.0.0rc2"; # differentiating these is important for rc's
+  version = "6.0.0rc3"; # differentiating these is important for rc's
 
   fetch = name: sha256: fetchurl {
-    url = "http://prereleases.llvm.org/${release_version}/rc2/${name}-${version}.src.tar.xz";
+    url = "http://prereleases.llvm.org/${release_version}/rc3/${name}-${version}.src.tar.xz";
     inherit sha256;
   };
 
-  compiler-rt_src = fetch "compiler-rt" "1ajk4iykgppc3wxij552m0qnj4rx3z1yyxj2yxhffwpsf973x68j";
-  clang-tools-extra_src = fetch "clang-tools-extra" "0vhaq3yq97w82jvq3w6ccvciwg7zp78b7s1246f3xdai6ijgk8g3";
+  compiler-rt_src = fetch "compiler-rt" "1lv5xawwn0spisa7jknq247pdndh4mlj22z1s0d7a5gqy9y0rlwv";
+  clang-tools-extra_src = fetch "clang-tools-extra" "0qv7rl8cpsj0l2xl5iym6ymxi3906mb2yx95mcf5ihlwjcms5klf";
 
   # Add man output without introducing extra dependencies.
   overrideManOutput = drv:
diff --git a/pkgs/development/compilers/llvm/6/libc++/default.nix b/pkgs/development/compilers/llvm/6/libc++/default.nix
index 5093c2687867..a1d1a17f2782 100644
--- a/pkgs/development/compilers/llvm/6/libc++/default.nix
+++ b/pkgs/development/compilers/llvm/6/libc++/default.nix
@@ -3,7 +3,7 @@
 stdenv.mkDerivation rec {
   name = "libc++-${version}";
 
-  src = fetch "libcxx" "0rpgd25v4h7dgvmqjnksgjmss3lhqzah57lfirpskdllcj9cfa9z";
+  src = fetch "libcxx" "1dvnvxx588wdyxbn18fwpyjxgypn316arz48zqll03z6zi2rqisa";
 
   postUnpack = ''
     unpackFile ${libcxxabi.src}
diff --git a/pkgs/development/compilers/llvm/6/libc++abi.nix b/pkgs/development/compilers/llvm/6/libc++abi.nix
index 62b6bf58627a..c33f0c126cfc 100644
--- a/pkgs/development/compilers/llvm/6/libc++abi.nix
+++ b/pkgs/development/compilers/llvm/6/libc++abi.nix
@@ -3,7 +3,7 @@
 stdenv.mkDerivation {
   name = "libc++abi-${version}";
 
-  src = fetch "libcxxabi" "10rc7r33bhz4fflnqdian9jvgf1r85p9qxkkgr78wxc7680f0ccx";
+  src = fetch "libcxxabi" "04m1w7a1cxwr6dqlilp0vn6jfjwd9al3nv1sfmypi01r90w69n0r";
 
   nativeBuildInputs = [ cmake ];
   buildInputs = stdenv.lib.optional (!stdenv.isDarwin && !stdenv.isFreeBSD) libunwind;
diff --git a/pkgs/development/compilers/llvm/6/lld.nix b/pkgs/development/compilers/llvm/6/lld.nix
index f52d5e70fef2..25b7edbe6c0f 100644
--- a/pkgs/development/compilers/llvm/6/lld.nix
+++ b/pkgs/development/compilers/llvm/6/lld.nix
@@ -10,7 +10,7 @@
 stdenv.mkDerivation {
   name = "lld-${version}";
 
-  src = fetch "lld" "0wj8rwd4bqh32p03hksy9bngv5pwrwmlxglslm8clwlxrc2rkb1f";
+  src = fetch "lld" "16nzzi233kknb3sz0hvwypfp6wa1d6rc7izf0v5zzhgrcr86yy98";
 
   nativeBuildInputs = [ cmake ];
   buildInputs = [ llvm libxml2 ];
diff --git a/pkgs/development/compilers/llvm/6/lldb.nix b/pkgs/development/compilers/llvm/6/lldb.nix
index 8890f154b4f3..264f2dc6f7b2 100644
--- a/pkgs/development/compilers/llvm/6/lldb.nix
+++ b/pkgs/development/compilers/llvm/6/lldb.nix
@@ -17,7 +17,7 @@
 stdenv.mkDerivation {
   name = "lldb-${version}";
 
-  src = fetch "lldb" "118yj804rgg5fwdj9j2yydamgfqx7c585ahiyap26x09cz5g2l1v";
+  src = fetch "lldb" "00gkkxsmz1dgj00mcv8ghxgi51skwbrfdw5rxqx27ay1pqbwa1zl";
 
   postPatch = ''
     # Fix up various paths that assume llvm and clang are installed in the same place
diff --git a/pkgs/development/compilers/llvm/6/llvm.nix b/pkgs/development/compilers/llvm/6/llvm.nix
index 9f3bd41c6ae8..e45e2ec75f13 100644
--- a/pkgs/development/compilers/llvm/6/llvm.nix
+++ b/pkgs/development/compilers/llvm/6/llvm.nix
@@ -20,7 +20,7 @@
 }:
 
 let
-  src = fetch "llvm" "1jnk30b7csdldar88pws2b000k3n1484k6gg2sxgz2fc6j7ldkzn";
+  src = fetch "llvm" "10qwr79kgkziqsaymszx36n265k0rpcr5c86xasi46rcigy59x4a";
 
   # Used when creating a version-suffixed symlink of libLLVM.dylib
   shortVersion = with stdenv.lib;
diff --git a/pkgs/development/compilers/llvm/6/openmp.nix b/pkgs/development/compilers/llvm/6/openmp.nix
index dc1b9b32544f..9461e8b8421a 100644
--- a/pkgs/development/compilers/llvm/6/openmp.nix
+++ b/pkgs/development/compilers/llvm/6/openmp.nix
@@ -10,7 +10,7 @@
 stdenv.mkDerivation {
   name = "openmp-${version}";
 
-  src = fetch "openmp" "1jz7i7gw8yazkn9hxsnq2lw9mj60g4wff4529yhx956jq1g1mr0k";
+  src = fetch "openmp" "1lgsn70rsmmc52qynd2r05bq34cllzyxb40vsqqv2vl3kicjis5k";
 
   nativeBuildInputs = [ cmake perl ];
   buildInputs = [ llvm ];