Index: llvm/trunk/cmake/modules/LLVMExternalProjectUtils.cmake
===================================================================
--- llvm/trunk/cmake/modules/LLVMExternalProjectUtils.cmake
+++ llvm/trunk/cmake/modules/LLVMExternalProjectUtils.cmake
@@ -95,7 +95,7 @@
   foreach(prefix ${ARG_PASSTHROUGH_PREFIXES})
     foreach(variableName ${variableNames})
       if(variableName MATCHES "^${prefix}")
-        string(REPLACE ";" "\;" value "${${variableName}}")
+        string(REPLACE ";" "," value "${${variableName}}")
         list(APPEND PASSTHROUGH_VARIABLES
           -D${variableName}=${value})
       endif()
@@ -159,6 +159,7 @@
     USES_TERMINAL_CONFIGURE 1
     USES_TERMINAL_BUILD 1
     USES_TERMINAL_INSTALL 1
+    LIST_SEPARATOR ,
     )
 
   if(ARG_USE_TOOLCHAIN)