Index: lib/CodeGen/CGCall.h
===================================================================
--- lib/CodeGen/CGCall.h
+++ lib/CodeGen/CGCall.h
@@ -204,12 +204,9 @@
       assert(isVirtual());
       return VirtualInfo.Addr;
     }
-
-    llvm::FunctionType *getFunctionType() const {
-      if (isVirtual())
-        return VirtualInfo.FTy;
-      return cast<llvm::FunctionType>(
-          getFunctionPointer()->getType()->getPointerElementType());
+    llvm::FunctionType *getVirtualFunctionType() const {
+      assert(isVirtual());
+      return VirtualInfo.FTy;
     }
 
     /// If this is a delayed callee computation of some sort, prepare
Index: lib/CodeGen/CGCall.cpp
===================================================================
--- lib/CodeGen/CGCall.cpp
+++ lib/CodeGen/CGCall.cpp
@@ -3826,7 +3826,7 @@
   QualType RetTy = CallInfo.getReturnType();
   const ABIArgInfo &RetAI = CallInfo.getReturnInfo();
 
-  llvm::FunctionType *IRFuncTy = Callee.getFunctionType();
+  llvm::FunctionType *IRFuncTy = getTypes().GetFunctionType(CallInfo);
 
 #ifndef NDEBUG
   if (!(CallInfo.isVariadic() && CallInfo.getArgStruct())) {
@@ -3837,8 +3837,13 @@
     //
     // In other cases, we assert that the types match up (until pointers stop
     // having pointee types).
-    llvm::FunctionType *IRFuncTyFromInfo = getTypes().GetFunctionType(CallInfo);
-    assert(IRFuncTy == IRFuncTyFromInfo);
+    llvm::Type *TypeFromVal;
+    if (Callee.isVirtual())
+      TypeFromVal = Callee.getVirtualFunctionType();
+    else
+      TypeFromVal =
+          Callee.getFunctionPointer()->getType()->getPointerElementType();
+    assert(IRFuncTy == TypeFromVal);
   }
 #endif
 
@@ -4207,8 +4212,8 @@
       // cases, we can't do any parameter mismatch checks.  Give up and bitcast
       // the callee.
       unsigned CalleeAS = CalleePtr->getType()->getPointerAddressSpace();
-      auto FnTy = getTypes().GetFunctionType(CallInfo)->getPointerTo(CalleeAS);
-      CalleePtr = Builder.CreateBitCast(CalleePtr, FnTy);
+      CalleePtr =
+          Builder.CreateBitCast(CalleePtr, IRFuncTy->getPointerTo(CalleeAS));
     } else {
       llvm::Type *LastParamTy =
           IRFuncTy->getParamType(IRFuncTy->getNumParams() - 1);
@@ -4240,19 +4245,20 @@
   //
   // This makes the IR nicer, but more importantly it ensures that we
   // can inline the function at -O0 if it is marked always_inline.
-  auto simplifyVariadicCallee = [](llvm::Value *Ptr) -> llvm::Value* {
-    llvm::FunctionType *CalleeFT =
-      cast<llvm::FunctionType>(Ptr->getType()->getPointerElementType());
+  auto simplifyVariadicCallee = [](llvm::FunctionType *CalleeFT,
+                                   llvm::Value *Ptr) -> llvm::Function * {
     if (!CalleeFT->isVarArg())
-      return Ptr;
+      return nullptr;
 
-    llvm::ConstantExpr *CE = dyn_cast<llvm::ConstantExpr>(Ptr);
-    if (!CE || CE->getOpcode() != llvm::Instruction::BitCast)
-      return Ptr;
+    // Get underlying value if it's a bitcast
+    if (llvm::ConstantExpr *CE = dyn_cast<llvm::ConstantExpr>(Ptr)) {
+      if (CE->getOpcode() == llvm::Instruction::BitCast)
+        Ptr = CE->getOperand(0);
+    }
 
-    llvm::Function *OrigFn = dyn_cast<llvm::Function>(CE->getOperand(0));
+    llvm::Function *OrigFn = dyn_cast<llvm::Function>(Ptr);
     if (!OrigFn)
-      return Ptr;
+      return nullptr;
 
     llvm::FunctionType *OrigFT = OrigFn->getFunctionType();
 
@@ -4261,15 +4267,19 @@
     if (OrigFT->isVarArg() ||
         OrigFT->getNumParams() != CalleeFT->getNumParams() ||
         OrigFT->getReturnType() != CalleeFT->getReturnType())
-      return Ptr;
+      return nullptr;
 
     for (unsigned i = 0, e = OrigFT->getNumParams(); i != e; ++i)
       if (OrigFT->getParamType(i) != CalleeFT->getParamType(i))
-        return Ptr;
+        return nullptr;
 
     return OrigFn;
   };
-  CalleePtr = simplifyVariadicCallee(CalleePtr);
+
+  if (llvm::Function *OrigFn = simplifyVariadicCallee(IRFuncTy, CalleePtr)) {
+    CalleePtr = OrigFn;
+    IRFuncTy = OrigFn->getFunctionType();
+  }
 
   // 3. Perform the actual call.
 
@@ -4364,10 +4374,10 @@
   // Emit the actual call/invoke instruction.
   llvm::CallBase *CI;
   if (!InvokeDest) {
-    CI = Builder.CreateCall(CalleePtr, IRCallArgs, BundleList);
+    CI = Builder.CreateCall(IRFuncTy, CalleePtr, IRCallArgs, BundleList);
   } else {
     llvm::BasicBlock *Cont = createBasicBlock("invoke.cont");
-    CI = Builder.CreateInvoke(CalleePtr, Cont, InvokeDest, IRCallArgs,
+    CI = Builder.CreateInvoke(IRFuncTy, CalleePtr, Cont, InvokeDest, IRCallArgs,
                               BundleList);
     EmitBlock(Cont);
   }
@@ -4591,7 +4601,7 @@
   if (isVirtual()) {
     const CallExpr *CE = getVirtualCallExpr();
     return CGF.CGM.getCXXABI().getVirtualFunctionPointer(
-        CGF, getVirtualMethodDecl(), getThisAddress(), getFunctionType(),
+        CGF, getVirtualMethodDecl(), getThisAddress(), getVirtualFunctionType(),
         CE ? CE->getBeginLoc() : SourceLocation());
   }