diff --git a/pkgs/development/compilers/llvm/3.9/clang/default.nix b/pkgs/development/compilers/llvm/3.9/clang/default.nix
index 9106822711038..ec2ec27df363d 100644
--- a/pkgs/development/compilers/llvm/3.9/clang/default.nix
+++ b/pkgs/development/compilers/llvm/3.9/clang/default.nix
@@ -13,7 +13,9 @@ let
       mv clang-tools-extra-* $sourceRoot/tools/extra
     '';
 
-    buildInputs = [ cmake libedit libxml2 llvm python ];
+    nativeBuildInputs = [ cmake ];
+
+    buildInputs = [ libedit libxml2 llvm python ];
 
     cmakeFlags = [
       "-DCMAKE_CXX_FLAGS=-std=c++11"
diff --git a/pkgs/development/compilers/llvm/3.9/llvm.nix b/pkgs/development/compilers/llvm/3.9/llvm.nix
index 2c47ec5127f96..964b6232fb549 100644
--- a/pkgs/development/compilers/llvm/3.9/llvm.nix
+++ b/pkgs/development/compilers/llvm/3.9/llvm.nix
@@ -15,10 +15,15 @@
 , compiler-rt_src
 , libcxxabi
 , debugVersion ? false
-, enableSharedLibraries ? true
+, enableSharedLibraries ? (buildPlatform == hostPlatform)
 , darwin
+, buildPackages
+, buildPlatform
+, hostPlatform
 }:
 
+assert (hostPlatform != buildPlatform) -> !enableSharedLibraries;
+
 let
   src = fetch "llvm" "1vi9sf7rx1q04wj479rsvxayb6z740iaz3qniwp266fgp5a07n8z";
   shlib = if stdenv.isDarwin then "dylib" else "so";
@@ -39,8 +44,17 @@ in stdenv.mkDerivation rec {
 
   outputs = [ "out" ] ++ stdenv.lib.optional enableSharedLibraries "lib";
 
-  buildInputs = [ perl groff cmake libxml2 python libffi ]
-    ++ stdenv.lib.optionals stdenv.isDarwin [ libcxxabi ];
+  nativeBuildInputs = [
+    perl
+    cmake
+    python
+  ];
+
+  buildInputs = [
+    groff
+    libxml2
+    libffi
+  ] ++ stdenv.lib.optionals stdenv.isDarwin [ libcxxabi ];
 
   propagatedBuildInputs = [ ncurses zlib ];
 
@@ -88,6 +102,9 @@ in stdenv.mkDerivation rec {
     ++ stdenv.lib.optionals (isDarwin) [
     "-DLLVM_ENABLE_LIBCXX=ON"
     "-DCAN_TARGET_i386=false"
+  ] ++ stdenv.lib.optionals (buildPlatform != hostPlatform) [
+    "-DCMAKE_CROSSCOMPILING=True"
+    "-DLLVM_TABLEGEN=${buildPackages.llvmPackages_39.llvm}/bin/llvm-tblgen"
   ];
 
   postBuild = ''
diff --git a/pkgs/tools/text/groff/default.nix b/pkgs/tools/text/groff/default.nix
index df6a1119800e7..aa9ece8955b4f 100644
--- a/pkgs/tools/text/groff/default.nix
+++ b/pkgs/tools/text/groff/default.nix
@@ -1,6 +1,7 @@
 { stdenv, fetchurl, perl, groff
 , ghostscript #for postscript and html output
 , psutils, netpbm #for html output
+, buildPackages
 }:
 
 stdenv.mkDerivation rec {
@@ -49,7 +50,7 @@ stdenv.mkDerivation rec {
     # Trick to get the build system find the proper 'native' groff
     # http://www.mail-archive.com/bug-groff@gnu.org/msg01335.html
     preBuild = ''
-      makeFlags="GROFF_BIN_PATH=${groff}/bin GROFFBIN=${groff}/bin/groff"
+      makeFlags="GROFF_BIN_PATH=${buildPackages.groff}/bin GROFFBIN=${buildPackages.groff}/bin/groff"
     '';
   };