Index: llvm/trunk/cmake/modules/AddLLVM.cmake
===================================================================
--- llvm/trunk/cmake/modules/AddLLVM.cmake
+++ llvm/trunk/cmake/modules/AddLLVM.cmake
@@ -1,5 +1,6 @@
 include(LLVMProcessSources)
 include(LLVM-Config)
+include(DetermineGCCCompatible)
 
 function(llvm_update_compile_flags name)
   get_property(sources TARGET ${name} PROPERTY SOURCES)
Index: llvm/trunk/cmake/modules/DetermineGCCCompatible.cmake
===================================================================
--- llvm/trunk/cmake/modules/DetermineGCCCompatible.cmake
+++ llvm/trunk/cmake/modules/DetermineGCCCompatible.cmake
@@ -0,0 +1,11 @@
+# Determine if the compiler has GCC-compatible command-line syntax.
+
+if(NOT DEFINED LLVM_COMPILER_IS_GCC_COMPATIBLE)
+  if(CMAKE_COMPILER_IS_GNUCXX)
+    set(LLVM_COMPILER_IS_GCC_COMPATIBLE ON)
+  elseif( MSVC )
+    set(LLVM_COMPILER_IS_GCC_COMPATIBLE OFF)
+  elseif( "${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang" )
+    set(LLVM_COMPILER_IS_GCC_COMPATIBLE ON)
+  endif()
+endif()
Index: llvm/trunk/cmake/modules/HandleLLVMStdlib.cmake
===================================================================
--- llvm/trunk/cmake/modules/HandleLLVMStdlib.cmake
+++ llvm/trunk/cmake/modules/HandleLLVMStdlib.cmake
@@ -1,17 +1,11 @@
 # This CMake module is responsible for setting the standard library to libc++
 # if the user has requested it.
 
+include(DetermineGCCCompatible)
+
 if(NOT DEFINED LLVM_STDLIB_HANDLED)
   set(LLVM_STDLIB_HANDLED ON)
 
-  if(CMAKE_COMPILER_IS_GNUCXX)
-    set(LLVM_COMPILER_IS_GCC_COMPATIBLE ON)
-  elseif( MSVC )
-    set(LLVM_COMPILER_IS_GCC_COMPATIBLE OFF)
-  elseif( "${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang" )
-    set(LLVM_COMPILER_IS_GCC_COMPATIBLE ON)
-  endif()
-
   function(append value)
     foreach(variable ${ARGN})
       set(${variable} "${${variable}} ${value}" PARENT_SCOPE)