Index: cmake/modules/AddLLVM.cmake
===================================================================
--- cmake/modules/AddLLVM.cmake
+++ cmake/modules/AddLLVM.cmake
@@ -983,6 +983,8 @@
   set(HOST_CXX "${CMAKE_CXX_COMPILER} ${CMAKE_CXX_COMPILER_ARG1}")
   set(HOST_LDFLAGS "${CMAKE_EXE_LINKER_FLAGS}")
 
+  set(LIT_SITE_CFG_IN_HEADER  "## Autogenerated from ${input}\n## Do not edit!")
+
   configure_file(${input} ${output} @ONLY)
 endfunction()
 
Index: test/Unit/lit.site.cfg.in
===================================================================
--- test/Unit/lit.site.cfg.in
+++ test/Unit/lit.site.cfg.in
@@ -1,7 +1,7 @@
+@LIT_SITE_CFG_IN_HEADER@
+
 import sys
 
-## Autogenerated by LLVM/Clang configuration.
-# Do not edit!
 config.llvm_src_root = "@LLVM_SOURCE_DIR@"
 config.llvm_obj_root = "@LLVM_BINARY_DIR@"
 config.llvm_tools_dir = "@LLVM_TOOLS_DIR@"
Index: test/lit.site.cfg.in
===================================================================
--- test/lit.site.cfg.in
+++ test/lit.site.cfg.in
@@ -1,7 +1,7 @@
+@LIT_SITE_CFG_IN_HEADER@
+
 import sys
 
-## Autogenerated by LLVM/Clang configuration.
-# Do not edit!
 config.host_triple = "@LLVM_HOST_TRIPLE@"
 config.target_triple = "@TARGET_TRIPLE@"
 config.llvm_src_root = "@LLVM_SOURCE_DIR@"