Index: clang-tools-extra/test/CMakeLists.txt
===================================================================
--- clang-tools-extra/test/CMakeLists.txt
+++ clang-tools-extra/test/CMakeLists.txt
@@ -20,13 +20,17 @@
   CLANGD_BUILD_XPC_SUPPORT)
 
 configure_lit_site_cfg(
-  ${CMAKE_CURRENT_SOURCE_DIR}/lit.site.cfg.in
-  ${CMAKE_CURRENT_BINARY_DIR}/lit.site.cfg
+  ${CMAKE_CURRENT_SOURCE_DIR}/lit.site.cfg.py.in
+  ${CMAKE_CURRENT_BINARY_DIR}/lit.site.cfg.py
+  MAIN_CONFIG
+  ${CMAKE_CURRENT_SOURCE_DIR}/lit.cfg.py
   )
 
 configure_lit_site_cfg(
-  ${CMAKE_CURRENT_SOURCE_DIR}/Unit/lit.site.cfg.in
-  ${CMAKE_CURRENT_BINARY_DIR}/Unit/lit.site.cfg
+  ${CMAKE_CURRENT_SOURCE_DIR}/Unit/lit.site.cfg.py.in
+  ${CMAKE_CURRENT_BINARY_DIR}/Unit/lit.site.cfg.py
+  MAIN_CONFIG
+  ${CMAKE_CURRENT_SOURCE_DIR}/Unit/lit.cfg.py
   )
 
 option(CLANG_TOOLS_TEST_USE_VG "Run Clang tools' tests under Valgrind" OFF)
Index: clang-tools-extra/test/Unit/lit.site.cfg.py.in
===================================================================
--- clang-tools-extra/test/Unit/lit.site.cfg.py.in
+++ clang-tools-extra/test/Unit/lit.site.cfg.py.in
@@ -6,4 +6,4 @@
 config.shlibdir = "@SHLIBDIR@"
 config.target_triple = "@TARGET_TRIPLE@"
 
-lit_config.load_config(config, "@CLANG_TOOLS_SOURCE_DIR@/test/Unit/lit.cfg")
+lit_config.load_config(config, "@CLANG_TOOLS_SOURCE_DIR@/test/Unit/lit.cfg.py")
Index: clang-tools-extra/test/lit.site.cfg.py.in
===================================================================
--- clang-tools-extra/test/lit.site.cfg.py.in
+++ clang-tools-extra/test/lit.site.cfg.py.in
@@ -28,4 +28,4 @@
 lit.llvm.initialize(lit_config, config)
 
 # Let the main config do the real work.
-lit_config.load_config(config, "@CLANG_TOOLS_SOURCE_DIR@/test/lit.cfg")
+lit_config.load_config(config, "@CLANG_TOOLS_SOURCE_DIR@/test/lit.cfg.py")