Index: llvm/lib/CodeGen/Analysis.cpp
===================================================================
--- llvm/lib/CodeGen/Analysis.cpp
+++ llvm/lib/CodeGen/Analysis.cpp
@@ -533,6 +533,7 @@
   // longjmp on x86), it can end up causing miscompilation that has not
   // been fully understood.
   if (!Ret && ((!TM.Options.GuaranteedTailCallOpt &&
+                !Call.isMustTailCall() &&
                 Call.getCallingConv() != CallingConv::Tail &&
                 Call.getCallingConv() != CallingConv::SwiftTail) ||
                !isa<UnreachableInst>(Term)))
Index: llvm/lib/IR/Verifier.cpp
===================================================================
--- llvm/lib/IR/Verifier.cpp
+++ llvm/lib/IR/Verifier.cpp
@@ -3505,11 +3505,13 @@
   }
 
   // Check the return.
-  ReturnInst *Ret = dyn_cast_or_null<ReturnInst>(Next);
-  Check(Ret, "musttail call must precede a ret with an optional bitcast", &CI);
-  Check(!Ret->getReturnValue() || Ret->getReturnValue() == RetVal ||
+  if (ReturnInst *Ret = dyn_cast_or_null<ReturnInst>(Next)) {
+    Check(!Ret->getReturnValue() || Ret->getReturnValue() == RetVal ||
             isa<UndefValue>(Ret->getReturnValue()),
         "musttail call result must be returned", Ret);
+  } else if (!Next || !isa<UnreachableInst>(Next))
+    CheckFailed("musttail call must precede a ret or unreachable with an "
+                "optional bitcast");
 
   AttributeList CallerAttrs = F->getAttributes();
   AttributeList CalleeAttrs = CI.getAttributes();
Index: llvm/test/CodeGen/AArch64/musttail-noreturn.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/AArch64/musttail-noreturn.ll
@@ -0,0 +1,10 @@
+; RUN: llc -mtriple=aarch64-linux-gnu %s -o  - | FileCheck %s
+
+define void @caller() {
+; CHECK: caller:
+; CHECK:     b callee
+  musttail call void @callee() noreturn
+  unreachable
+}
+
+declare void @callee() noreturn
Index: llvm/test/CodeGen/ARM/musttail-noreturn.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/ARM/musttail-noreturn.ll
@@ -0,0 +1,10 @@
+; RUN: llc -mtriple=thumbv7k-apple-watchos4 %s -o  - | FileCheck %s
+
+define void @caller() {
+; CHECK: caller:
+; CHECK:     b.w _callee
+  musttail call void @callee() noreturn
+  unreachable
+}
+
+declare void @callee() noreturn
Index: llvm/test/CodeGen/X86/musttail-noreturn.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/X86/musttail-noreturn.ll
@@ -0,0 +1,10 @@
+; RUN: llc -mtriple=x86_64-linux-gnu %s -o  - | FileCheck %s
+
+define void @caller() {
+; CHECK: caller:
+; CHECK:     jmp callee
+  musttail call void @callee() noreturn
+  unreachable
+}
+
+declare void @callee() noreturn
Index: llvm/test/Verifier/musttail-invalid.ll
===================================================================
--- llvm/test/Verifier/musttail-invalid.ll
+++ llvm/test/Verifier/musttail-invalid.ll
@@ -70,7 +70,7 @@
 
 declare i32 @not_tail_pos_callee()
 define i32 @not_tail_pos() {
-; CHECK: musttail call must precede a ret with an optional bitcast
+; CHECK: musttail call must precede a ret or unreachable with an optional bitcast
   %v = musttail call i32 @not_tail_pos_callee()
   %w = add i32 %v, 1
   ret i32 %w
Index: llvm/test/Verifier/musttail-valid.ll
===================================================================
--- llvm/test/Verifier/musttail-valid.ll
+++ llvm/test/Verifier/musttail-valid.ll
@@ -37,3 +37,9 @@
 bb1:
   ret void
 }
+
+define void @noreturn_caller() {
+  musttail call void @noreturn_callee() noreturn
+  unreachable
+}
+declare void @noreturn_callee() noreturn