diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index 9cfdfdc..34154f3 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -926,8 +926,10 @@
 
   // -fblocks=0 is default.
   if (Args.hasFlag(options::OPT_fblocks, options::OPT_fno_blocks,
-                   getToolChain().IsBlocksDefault()))
+                   getToolChain().IsBlocksDefault())) {
+    Args.AddLastArg(CmdArgs, options::OPT_fblock_introspection);
     CmdArgs.push_back("-fblocks");
+  }
 
   if (needsExceptions(Args, InputType, getToolChain().getTriple()))
     CmdArgs.push_back("-fexceptions");