diff --git a/llvm/lib/Support/Windows/Process.inc b/llvm/lib/Support/Windows/Process.inc
--- a/llvm/lib/Support/Windows/Process.inc
+++ b/llvm/lib/Support/Windows/Process.inc
@@ -158,7 +158,7 @@
   // the common case. Also don't wildcard expand /?. Always treat it as an
   // option.
   if (Arg.find_first_of("*?") == StringRef::npos || Arg == "/?" ||
-      Arg == "-?") {
+      Arg == "-?" || Arg.startswith("\\\\?\\")) {
     Args.push_back(Arg.data());
     return EC;
   }