Index: llvm/lib/Analysis/InlineCost.cpp
===================================================================
--- llvm/lib/Analysis/InlineCost.cpp
+++ llvm/lib/Analysis/InlineCost.cpp
@@ -1960,6 +1960,16 @@
   if (!Callee)
     return llvm::InlineCost::getNever();
 
+  // Never inline functions with musttail intrinsics. Currently the only
+  // possible such intrinsic is llvm.icall.branch.funnel and it does not work
+  // with inlining.
+  for (const auto &BB : *Callee)
+    for (const auto &I : BB)
+      if (const CallInst *CI = dyn_cast<CallInst>(&I))
+        if (const Function *F = CI->getCalledFunction())
+          if (CI->isMustTailCall() && F->isIntrinsic())
+            return llvm::InlineCost::getNever();
+
   // Never inline calls with byval arguments that does not have the alloca
   // address space. Since byval arguments can be replaced with a copy to an
   // alloca, the inlined code would need to be adjusted to handle that the
Index: llvm/test/Transforms/WholeProgramDevirt/branch-funnel.ll
===================================================================
--- llvm/test/Transforms/WholeProgramDevirt/branch-funnel.ll
+++ llvm/test/Transforms/WholeProgramDevirt/branch-funnel.ll
@@ -1,6 +1,10 @@
 ; RUN: opt -S -wholeprogramdevirt %s | FileCheck --check-prefixes=CHECK,RETP %s
 ; RUN: sed -e 's,+retpoline,-retpoline,g' %s | opt -S -wholeprogramdevirt | FileCheck --check-prefixes=CHECK,NORETP %s
+
 ; RUN: opt -wholeprogramdevirt -wholeprogramdevirt-summary-action=export -wholeprogramdevirt-read-summary=%S/Inputs/export.yaml -wholeprogramdevirt-write-summary=%t -S -o - %s | FileCheck --check-prefixes=CHECK,RETP %s
+
+; RUN: opt -wholeprogramdevirt -wholeprogramdevirt-summary-action=export -wholeprogramdevirt-read-summary=%S/Inputs/export.yaml -wholeprogramdevirt-write-summary=%t  -O3 -S -o - %s | FileCheck --check-prefixes=CHECK %s
+
 ; RUN: FileCheck --check-prefix=SUMMARY %s < %t
 
 ; SUMMARY:      TypeIdMap:       
@@ -89,7 +93,10 @@
 declare i32 @vf4_1(i8* %this, i32 %arg)
 declare i32 @vf4_2(i8* %this, i32 %arg)
 
-; CHECK: define i32 @fn1
+
+
+; CHECK-LABEL: define i32 @fn1
+; CHECK-NOT: call void (...) @llvm.icall.branch.funnel
 define i32 @fn1(i8* %obj) #0 {
   %vtableptr = bitcast i8* %obj to [1 x i8*]**
   %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
@@ -107,7 +114,8 @@
   ret i32 %result
 }
 
-; CHECK: define i32 @fn2
+; CHECK-LABEL: define i32 @fn2
+; CHECK-NOT: call void (...) @llvm.icall.branch.funnel
 define i32 @fn2(i8* %obj) #0 {
   %vtableptr = bitcast i8* %obj to [1 x i8*]**
   %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
@@ -122,7 +130,8 @@
   ret i32 %result
 }
 
-; CHECK: define i32 @fn3
+; CHECK-LABEL: define i32 @fn3
+; CHECK-NOT: call void (...) @llvm.icall.branch.funnel
 define i32 @fn3(i8* %obj) #0 {
   %vtableptr = bitcast i8* %obj to [1 x i8*]**
   %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
@@ -138,10 +147,9 @@
   ret i32 %result
 }
 
-; CHECK: define internal void @branch_funnel(i8* nest, ...)
-
+; CHECK-LABEL: define internal void @branch_funnel(i8*
 ; CHECK: define hidden void @__typeid_typeid1_0_branch_funnel(i8* nest, ...)
-; CHECK-NEXT: call void (...) @llvm.icall.branch.funnel(i8* %0, i8* bitcast ([1 x i8*]* @vt1_1 to i8*), i32 (i8*, i32)* @vf1_1, i8* bitcast ([1 x i8*]* @vt1_2 to i8*), i32 (i8*, i32)* @vf1_2, ...)
+; CHECK-NEXT: musttail call void (...) @llvm.icall.branch.funnel(i8* %0, i8* bitcast ([1 x i8*]* {{(nonnull )?}}@vt1_1 to i8*), i32 (i8*, i32)* {{(nonnull )?}}@vf1_1, i8* bitcast ([1 x i8*]* {{(nonnull )?}}@vt1_2 to i8*), i32 (i8*, i32)* {{(nonnull )?}}@vf1_2, ...)
 
 declare i1 @llvm.type.test(i8*, metadata)
 declare void @llvm.assume(i1)