--- a/llvm/CMakeLists.txt
+++ b/llvm/CMakeLists.txt
@@ -9,7 +9,9 @@
     "at least 3.20.0 now to avoid issues in the future!")
 endif()

-set(LLVM_COMMON_CMAKE_UTILS ${CMAKE_CURRENT_SOURCE_DIR}/../cmake)
+if(NOT DEFINED LLVM_COMMON_CMAKE_UTILS)
+  set(LLVM_COMMON_CMAKE_UTILS ${CMAKE_CURRENT_SOURCE_DIR}/../cmake)
+endif()
 include(${LLVM_COMMON_CMAKE_UTILS}/Modules/CMakePolicy.cmake
   NO_POLICY_SCOPE)