Index: CMakeLists.txt
===================================================================
--- CMakeLists.txt
+++ CMakeLists.txt
@@ -419,7 +419,14 @@
 add_subdirectory(examples)
 
 if( CLANG_INCLUDE_TESTS )
-  if(EXISTS ${LLVM_MAIN_SRC_DIR}/utils/unittest/googletest/include/gtest/gtest.h)
+  if(TARGET gtest)
+    if(NOT EXISTS ${LLVM_MAIN_SRC_DIR}/utils/unittest/googletest/include/gtest/gtest.h)
+      # add include directories for installed llvm-gtest
+      foreach(incdir ${LLVM_INCLUDE_DIRS})
+        include_directories("${incdir}/llvm-gtest")
+      endforeach()
+    endif()
+
     add_subdirectory(unittests)
     list(APPEND CLANG_TEST_DEPS ClangUnitTests)
     list(APPEND CLANG_TEST_PARAMS