Index: lib/AST/MicrosoftMangle.cpp
===================================================================
--- lib/AST/MicrosoftMangle.cpp
+++ lib/AST/MicrosoftMangle.cpp
@@ -950,11 +950,10 @@
   }
 }

+// <postfix> ::= <unqualified-name> [<postfix>]
+//           ::= <substitution> [<postfix>]
 void MicrosoftCXXNameMangler::mangleNestedName(const NamedDecl *ND) {
-  // <postfix> ::= <unqualified-name> [<postfix>]
-  //           ::= <substitution> [<postfix>]
   const DeclContext *DC = getEffectiveDeclContext(ND);
-
   while (!DC->isTranslationUnit()) {
     if (isa<TagDecl>(ND) || isa<VarDecl>(ND)) {
       unsigned Disc;
@@ -2151,6 +2150,7 @@
     case CC_X86StdCall: Out << 'G'; break;
     case CC_X86FastCall: Out << 'I'; break;
     case CC_X86VectorCall: Out << 'Q'; break;
+    case CC_Swift: Out << 'S'; break;
     case CC_X86RegCall: Out << 'w'; break;
   }
 }
Index: test/CodeGenCXX/msabi-swiftcall-cc.cpp
===================================================================
--- /dev/null
+++ test/CodeGenCXX/msabi-swiftcall-cc.cpp
@@ -0,0 +1,28 @@
+// RUN: %clang_cc1 -triple i686-unknown-windows-msvc -fdeclspec -emit-llvm %s -o - | FileCheck %s
+
+void __attribute__((__swiftcall__)) f() {}
+// CHECK-DAG: @"\01?f@@YSXXZ"
+
+void (__attribute__((__swiftcall__)) *p)();
+// CHECK-DAG: @"\01?p@@3P6SXXZA"
+
+namespace {
+void __attribute__((__swiftcall__)) __attribute__((__used__)) f() { }
+// CHECK-DAG: "\01?f@?A@@YSXXZ"
+}
+
+namespace n {
+void __attribute__((__swiftcall__)) f() {}
+// CHECK-DAG: "\01?f@n@@YSXXZ"
+}
+
+struct __declspec(dllexport) S {
+  S(const S &) = delete;
+  S & operator=(const S &) = delete;
+  void __attribute__((__swiftcall__)) m() { }
+  // CHECK-DAG: "\01?m@S@@QASXXZ"
+};
+
+void f(void (__attribute__((__swiftcall__))())) {}
+// CHECK-DAG: "\01?f@@YAXP6SXXZ@Z"
+