diff --git a/llvm/lib/Support/Unix/Path.inc b/llvm/lib/Support/Unix/Path.inc
--- a/llvm/lib/Support/Unix/Path.inc
+++ b/llvm/lib/Support/Unix/Path.inc
@@ -815,6 +815,9 @@
 
   int flags = (Mode == readwrite) ? MAP_SHARED : MAP_PRIVATE;
   int prot = (Mode == readonly) ? PROT_READ : (PROT_READ | PROT_WRITE);
+#if defined(MAP_NORESERVE)
+  flags |= MAP_NORESERVE;
+#endif
 #if defined(__APPLE__)
   //----------------------------------------------------------------------
   // Newer versions of MacOSX have a flag that will allow us to read from