diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 291ff8e..0e93e40 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -673,7 +673,16 @@
   } else {
     IdentifierInfo *II = ND->getIdentifier();
     assert(II && "Attempt to mangle unnamed decl.");
-    Str = II->getName();
+    const auto *FD = dyn_cast<FunctionDecl>(ND);
+
+    if (FD &&
+        FD->getType()->castAs<FunctionType>()->getCallConv() == CC_X86RegCall) {
+      llvm::raw_svector_ostream Out(Buffer);
+      Out << "__regcall3__" << II->getName();
+      Str = Out.str();
+    } else {
+      Str = II->getName();
+    }
   }
 
   // Keep the first result in the case of a mangling collision.