diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index 1eec2f2..bc6ad14 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -887,9 +887,7 @@
   Args.AddLastArg(CmdArgs, options::OPT_femit_all_decls);
   Args.AddLastArg(CmdArgs, options::OPT_ffreestanding);
   Args.AddLastArg(CmdArgs, options::OPT_fheinous_gnu_extensions);
-  Args.AddLastArg(CmdArgs, options::OPT_fgnu_runtime);
   Args.AddLastArg(CmdArgs, options::OPT_flax_vector_conversions);
-  Args.AddLastArg(CmdArgs, options::OPT_fnext_runtime);
   Args.AddLastArg(CmdArgs, options::OPT_fno_caret_diagnostics);
   Args.AddLastArg(CmdArgs, options::OPT_fno_show_column);
   Args.AddLastArg(CmdArgs, options::OPT_fobjc_gc_only);
@@ -955,6 +953,12 @@
                    getToolChain().getTriple().getOS() == llvm::Triple::Win32))
     CmdArgs.push_back("-fms-extensions");
 
+  // -fnext-runtime is default.
+  if (!Args.hasFlag(options::OPT_fnext_runtime,
+                    options::OPT_fgnu_runtime,
+                    getToolChain().getTriple().getOS() == llvm::Triple::Darwin))
+    CmdArgs.push_back("-fgnu-runtime");
+
   // -fshort-wchar default varies depending on platform; only
   // pass if specified.
   if (Arg *A = Args.getLastArg(options::OPT_fshort_wchar)) {