Index: clang-tools-extra/trunk/unittests/CMakeLists.txt
===================================================================
--- clang-tools-extra/trunk/unittests/CMakeLists.txt
+++ clang-tools-extra/trunk/unittests/CMakeLists.txt
@@ -5,6 +5,15 @@
   add_unittest(ExtraToolsUnitTests ${test_dirname} ${ARGN})
 endfunction()
 
+if(CLANG_BUILT_STANDALONE)
+  # LLVMTestingSupport library is needed for clangd tests.
+  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_subdirectory(change-namespace)
 add_subdirectory(clang-apply-replacements)
 add_subdirectory(clang-move)