diff --git a/pkgs/development/compilers/llvm/3.6/llvm.nix b/pkgs/development/compilers/llvm/3.6/llvm.nix
index a679ab3babd..736ffca295f 100644
--- a/pkgs/development/compilers/llvm/3.6/llvm.nix
+++ b/pkgs/development/compilers/llvm/3.6/llvm.nix
@@ -41,6 +41,7 @@ in stdenv.mkDerivation rec {
     "-DCMAKE_BUILD_TYPE=Release"
     "-DLLVM_BUILD_TESTS=ON"
     "-DLLVM_ENABLE_FFI=ON"
+    "-DLLVM_ENABLE_RTTI=ON"
   ] ++ stdenv.lib.optionals (!isDarwin) [
     "-DBUILD_SHARED_LIBS=ON"
     "-DLLVM_BINUTILS_INCDIR=${binutils}/include"