diff --git a/lib/Frontend/CompilerInvocation.cpp b/lib/Frontend/CompilerInvocation.cpp
index afba109..d25801a 100644
--- a/lib/Frontend/CompilerInvocation.cpp
+++ b/lib/Frontend/CompilerInvocation.cpp
@@ -1310,7 +1310,7 @@
   Opts.ObjCConstantStringClass =
     Args.getLastArgValue(OPT_fconstant_string_class);
   Opts.ObjCDefaultSynthProperties =
-    Args.hasArg(OPT_fobjc_default_synthesize_properties);
+    !Args.hasArg(OPT_disable_objc_default_synthesize_properties);
   Opts.EncodeExtendedBlockSig =
     Args.hasArg(OPT_fencode_extended_block_signature);
   Opts.EmitAllDecls = Args.hasArg(OPT_femit_all_decls);