Index: cmake/modules/AddLLVM.cmake
===================================================================
--- cmake/modules/AddLLVM.cmake
+++ cmake/modules/AddLLVM.cmake
@@ -1076,7 +1076,7 @@
   if (NOT CMAKE_CFG_INTDIR STREQUAL ".")
     list(APPEND LIT_ARGS --param build_mode=${CMAKE_CFG_INTDIR})
   endif ()
-  if (LLVM_MAIN_SRC_DIR)
+  if(EXISTS ${LLVM_MAIN_SRC_DIR}/utils/lit/lit.py)
     set (LIT_COMMAND ${PYTHON_EXECUTABLE} ${LLVM_MAIN_SRC_DIR}/utils/lit/lit.py)
   else()
     find_program(LIT_COMMAND llvm-lit)