diff --git a/clang/lib/AST/Mangle.cpp b/clang/lib/AST/Mangle.cpp
--- a/clang/lib/AST/Mangle.cpp
+++ b/clang/lib/AST/Mangle.cpp
@@ -36,11 +36,14 @@
                                 StringRef Outer,
                                 const BlockDecl *BD,
                                 raw_ostream &Out) {
-  unsigned discriminator = Context.getBlockId(BD, true);
-  if (discriminator == 0)
-    Out << "__" << Outer << "_block_invoke";
-  else
-    Out << "__" << Outer << "_block_invoke_" << discriminator+1;
+  Out << "__" << Outer << "_block_invoke__";
+
+  ArrayRef<ParmVarDecl *> params = BD->parameters();
+  for(unsigned i = 0; i < params.size(); i++) {
+    ParmVarDecl *param = params[i];
+    Out << "_";
+    Context.mangleTypeName(param->getType(), Out);
+  }
 }
 
 void MangleContext::anchor() { }