diff --git a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
--- a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -556,6 +556,21 @@
   }
 }
 
+// For a ret instruction followed by a musttail call, we cannot insert anything
+// in between and have to return the new insertion point as the call inst.
+static Instruction *adjustForMusttailCall(Instruction *I) {
+  ReturnInst *RI = dyn_cast<ReturnInst>(I);
+  if (!RI)
+    return I;
+  Instruction *Prev = RI->getPrevNode();
+  if (BitCastInst *BCI = dyn_cast_or_null<BitCastInst>(Prev))
+    Prev = BCI->getPrevNode();
+  if (CallInst *CI = dyn_cast_or_null<CallInst>(Prev))
+    if (CI->isMustTailCall())
+      return CI;
+  return RI;
+}
+
 namespace {
 
 /// Module analysis for getting various metadata about the module.
@@ -999,10 +1014,11 @@
 
   // Unpoison dynamic allocas redzones.
   void unpoisonDynamicAllocas() {
-    for (auto &Ret : RetVec)
-      unpoisonDynamicAllocasBeforeInst(Ret, DynamicAllocaLayout);
+    for (Instruction *Ret : RetVec)
+      unpoisonDynamicAllocasBeforeInst(adjustForMusttailCall(Ret),
+                                       DynamicAllocaLayout);
 
-    for (auto &StackRestoreInst : StackRestoreVec)
+    for (Instruction *StackRestoreInst : StackRestoreVec)
       unpoisonDynamicAllocasBeforeInst(StackRestoreInst,
                                        StackRestoreInst->getOperand(0));
   }
@@ -3303,7 +3319,8 @@
   SmallVector<uint8_t, 64> ShadowAfterReturn;
 
   // (Un)poison the stack before all ret instructions.
-  for (auto Ret : RetVec) {
+  for (Instruction *Ret : RetVec) {
+    Ret = adjustForMusttailCall(Ret);
     IRBuilder<> IRBRet(Ret);
     // Mark the current frame as retired.
     IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),