diff --git a/lib/CodeGen/CGCall.cpp b/lib/CodeGen/CGCall.cpp
index 0ecd976..37a9a5e 100644
--- a/lib/CodeGen/CGCall.cpp
+++ b/lib/CodeGen/CGCall.cpp
@@ -105,8 +105,12 @@
 /// Given the formal ext-info of a C++ instance method, adjust it
 /// according to the C++ ABI in effect.
 static void adjustCXXMethodInfo(CodeGenTypes &CGT,
-                                FunctionType::ExtInfo &extInfo) {
-  // FIXME: thiscall on Microsoft
+                                FunctionType::ExtInfo &extInfo,
+                                bool isVariadic) {
+  if (extInfo.getCC() == CC_Default) {
+    CallingConv CC = CGT.getContext().getDefaultCXXMethodCallConv(isVariadic);
+    extInfo = extInfo.withCallingConv(CC);
+  }
 }
 
 /// Arrange the argument and result information for a free function (i.e.
@@ -115,7 +119,7 @@
                                       SmallVectorImpl<CanQualType> &prefix,
                                             CanQual<FunctionProtoType> FTP) {
   FunctionType::ExtInfo extInfo = FTP->getExtInfo();
-  adjustCXXMethodInfo(CGT, extInfo);
+  adjustCXXMethodInfo(CGT, extInfo, FTP->isVariadic());
   return arrangeLLVMFunctionInfo(CGT, prefix, FTP, extInfo);
 }
 
@@ -202,7 +206,7 @@
     argTypes.push_back(FTP->getArgType(i));
 
   FunctionType::ExtInfo extInfo = FTP->getExtInfo();
-  adjustCXXMethodInfo(*this, extInfo);
+  adjustCXXMethodInfo(*this, extInfo, FTP->isVariadic());
   return arrangeLLVMFunctionInfo(resultType, argTypes, extInfo, required);
 }
 
@@ -220,9 +224,10 @@
 
   CanQual<FunctionProtoType> FTP = GetFormalType(D);
   assert(FTP->getNumArgs() == 0 && "dtor with formal parameters");
+  assert(FTP->isVariadic() == 0 && "dtor with formal parameters");
 
   FunctionType::ExtInfo extInfo = FTP->getExtInfo();
-  adjustCXXMethodInfo(*this, extInfo);
+  adjustCXXMethodInfo(*this, extInfo, false);
   return arrangeLLVMFunctionInfo(resultType, argTypes, extInfo,
                                  RequiredArgs::All);
 }
@@ -354,7 +359,7 @@
     argTypes.push_back(Context.getCanonicalParamType(i->Ty));
 
   FunctionType::ExtInfo info = FPT->getExtInfo();
-  adjustCXXMethodInfo(*this, info);
+  adjustCXXMethodInfo(*this, info, FPT->isVariadic());
   return arrangeLLVMFunctionInfo(GetReturnType(FPT->getResultType()),
                                  argTypes, info, required);
 }