diff --git a/llvm/cmake/modules/AddLLVM.cmake b/llvm/cmake/modules/AddLLVM.cmake
index a474071..303962b 100644
--- a/llvm/cmake/modules/AddLLVM.cmake
+++ b/llvm/cmake/modules/AddLLVM.cmake
@@ -1457,7 +1457,7 @@
 
   string(CONCAT LIT_SITE_CFG_IN_HEADER "${LIT_SITE_CFG_IN_HEADER}\n\n"
     "# Allow generated lit.site.cfg.py to be relocatable.\n"
-    "def path(p): return os.path.join(os.path.dirname(__file__), p) if p else ''\n"
+    "def path(p): return os.path.join(os.path.dirname(__file__), p).replace(os.sep, '/') if p else ''\n"
     )
 
   # Override config_target_triple (and the env)
@@ -1486,7 +1486,7 @@
     string(REPLACE ";" "\\;" ARG_PATH_VALUES_ESCAPED "${ARG_PATH_VALUES}")
     get_filename_component(OUTPUT_DIR ${site_out} DIRECTORY)
     execute_process(COMMAND "${PYTHON_EXECUTABLE}" "-c"
-      "import os, sys; sys.stdout.write(';'.join(os.path.relpath(p, sys.argv[1]).replace('\\\\', '/') if p else '' for p in sys.argv[2].split(';')))"
+      "import os, sys; sys.stdout.write(';'.join(os.path.relpath(p, sys.argv[1]).replace(os.sep, '/') if p else '' for p in sys.argv[2].split(';')))"
       ${OUTPUT_DIR}
       ${ARG_PATH_VALUES_ESCAPED}
       OUTPUT_VARIABLE ARG_PATH_VALUES_RELATIVE)