diff --git a/openmp/runtime/CMakeLists.txt b/openmp/runtime/CMakeLists.txt
index 6b896aa3ecd0..33225b6f3ccf 100644
--- a/openmp/runtime/CMakeLists.txt
+++ b/openmp/runtime/CMakeLists.txt
@@ -17,7 +17,8 @@ set(CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/cmake ${CMAKE_MODULE_PATH})
 
 # Standalone build or part of LLVM?
 set(LIBOMP_STANDALONE_BUILD FALSE)
-if("${CMAKE_SOURCE_DIR}" STREQUAL "${CMAKE_CURRENT_SOURCE_DIR}" OR
+if(OPENMP_STANDALONE_BUILD OR
+   "${CMAKE_SOURCE_DIR}" STREQUAL "${CMAKE_CURRENT_SOURCE_DIR}" OR
    "${CMAKE_SOURCE_DIR}/runtime" STREQUAL "${CMAKE_CURRENT_SOURCE_DIR}")
   project(libomp C CXX)
   set(LIBOMP_STANDALONE_BUILD TRUE)