Index: cfe/trunk/unittests/CMakeLists.txt
===================================================================
--- cfe/trunk/unittests/CMakeLists.txt
+++ cfe/trunk/unittests/CMakeLists.txt
@@ -1,6 +1,15 @@
 add_custom_target(ClangUnitTests)
 set_target_properties(ClangUnitTests PROPERTIES FOLDER "Clang tests")
 
+if(CLANG_BUILT_STANDALONE)
+  # LLVMTestingSupport library is needed for some of the unittests.
+  if (EXISTS ${LLVM_MAIN_SRC_DIR}/lib/Testing/Support
+      AND NOT TARGET LLVMTestingSupport)
+    add_subdirectory(${LLVM_MAIN_SRC_DIR}/lib/Testing/Support
+      lib/Testing/Support)
+  endif()
+endif()
+
 # add_clang_unittest(test_dirname file1.cpp file2.cpp)
 #
 # Will compile the list of files together and link against the clang