diff --git a/llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
--- a/llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
@@ -779,6 +779,7 @@
 
   void visitUnaryOperator(UnaryOperator &UO);
   void visitBinaryOperator(BinaryOperator &BO);
+  void visitBitCastInst(BitCastInst &BCI);
   void visitCastInst(CastInst &CI);
   void visitCmpInst(CmpInst &CI);
   void visitGetElementPtrInst(GetElementPtrInst &GEPI);
@@ -2774,6 +2775,19 @@
   visitInstOperands(BO);
 }
 
+void DFSanVisitor::visitBitCastInst(BitCastInst &BCI) {
+  if (DFSF.DFS.getInstrumentedABI() == DataFlowSanitizer::IA_TLS) {
+    // Special case: if this is the bitcast (there is exactly 1 allowed) between
+    // a musttail call and a ret, don't instrument. New instructions are not
+    // allowed after a musttail call.
+    if (auto *CI = dyn_cast<CallInst>(BCI.getOperand(0)))
+      if (CI->isMustTailCall())
+        return;
+  }
+  // TODO: handle musttail call returns for IA_Args.
+  visitInstOperands(BCI);
+}
+
 void DFSanVisitor::visitCastInst(CastInst &CI) { visitInstOperands(CI); }
 
 void DFSanVisitor::visitCmpInst(CmpInst &CI) {
@@ -2968,10 +2982,25 @@
   }
 }
 
+static bool isAMustTailRetVal(Value *RetVal) {
+  // Tail call may have a bitcast between return.
+  if (auto *I = dyn_cast<BitCastInst>(RetVal)) {
+    RetVal = I->getOperand(0);
+  }
+  if (auto *I = dyn_cast<CallInst>(RetVal)) {
+    return I->isMustTailCall();
+  }
+  return false;
+}
+
 void DFSanVisitor::visitReturnInst(ReturnInst &RI) {
   if (!DFSF.IsNativeABI && RI.getReturnValue()) {
     switch (DFSF.IA) {
     case DataFlowSanitizer::IA_TLS: {
+      // Don't emit the instrumentation for musttail call returns.
+      if (isAMustTailRetVal(RI.getReturnValue()))
+        return;
+
       Value *S = DFSF.getShadow(RI.getReturnValue());
       IRBuilder<> IRB(&RI);
       Type *RT = DFSF.F->getFunctionType()->getReturnType();
@@ -2990,6 +3019,8 @@
       break;
     }
     case DataFlowSanitizer::IA_Args: {
+      // TODO: handle musttail call returns for IA_Args.
+
       IRBuilder<> IRB(&RI);
       Type *RT = DFSF.F->getFunctionType()->getReturnType();
       Value *InsVal =
@@ -3265,6 +3296,10 @@
     }
 
     if (DFSF.DFS.getInstrumentedABI() == DataFlowSanitizer::IA_TLS) {
+      // Don't emit the epilogue for musttail call returns.
+      if (isa<CallInst>(CB) && cast<CallInst>(CB).isMustTailCall())
+        return;
+
       // Loads the return value shadow.
       IRBuilder<> NextIRB(Next);
       const DataLayout &DL = getDataLayout();
@@ -3293,6 +3328,8 @@
   // Do all instrumentation for IA_Args down here to defer tampering with the
   // CFG in a way that SplitEdge may be able to detect.
   if (DFSF.DFS.getInstrumentedABI() == DataFlowSanitizer::IA_Args) {
+    // TODO: handle musttail call returns for IA_Args.
+
     FunctionType *NewFT = DFSF.DFS.getArgsFunctionType(FT);
     Value *Func =
         IRB.CreateBitCast(CB.getCalledOperand(), PointerType::getUnqual(NewFT));
diff --git a/llvm/test/Instrumentation/DataFlowSanitizer/musttailcall.ll b/llvm/test/Instrumentation/DataFlowSanitizer/musttailcall.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Instrumentation/DataFlowSanitizer/musttailcall.ll
@@ -0,0 +1,67 @@
+; RUN: opt < %s -dfsan -S | FileCheck %s
+; RUN: opt < %s -dfsan -dfsan-fast-16-labels -S | FileCheck %s
+; RUN: opt < %s -dfsan -dfsan-fast-8-labels -S | FileCheck %s
+; RUN: opt < %s -dfsan -dfsan-fast-16-labels -dfsan-track-origins=1 -S | FileCheck %s --check-prefixes=CHECK,CHECK_ORIGIN
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; CHECK-LABEL: @__dfsan_arg_tls
+; CHECK: = external thread_local(initialexec) global [100 x i64]
+
+; CHECK-LABEL: @__dfsan_retval_tls
+; CHECK: = external thread_local(initialexec) global [100 x i64]
+
+declare i32 @f(i32)
+
+; CHECK-LABEL: @"dfs$inner_callee"
+define i32 @inner_callee(i32) {
+  %r = call i32 @f(i32 %0)
+
+  ; COMM: Store here will be loaded in @outer_caller
+  ; CHECK: store{{.*}}__dfsan_retval_tls
+  ; CHECK_ORIGIN-NEXT: store{{.*}}__dfsan_retval_origin_tls
+  ; CHECK-NEXT: ret i32
+  ret i32 %r
+}
+
+; CHECK-LABEL: @"dfs$musttail_call"
+define i32 @musttail_call(i32) {
+  ; CHECK: store{{.*}}__dfsan_arg_tls
+  ; CHECK-NEXT: musttail call i32 @"dfs$inner_callee"
+  %r = musttail call i32 @inner_callee(i32 %0)
+
+  ; For "musttail" calls we can not insert any shadow manipulating code between
+  ; call and the return instruction. And we don't need to, because everything is
+  ; taken care of in the callee.
+  ; This is similar to the function above, but the last load and store of
+  ; __dfsan_retval_tls can be elided because we know about the musttail.
+
+  ; CHECK-NEXT: ret i32
+  ret i32 %r
+}
+
+; CHECK-LABEL: @"dfs$outer_caller"
+define i32 @outer_caller() {
+  ; CHECK: call{{.*}}@"dfs$musttail_call"
+  ; CHECK-NEXT: load{{.*}}__dfsan_retval_tls
+  ; CHECK_ORIGIN-NEXT: load{{.*}}__dfsan_retval_origin_tls
+  %r = call i32 @musttail_call(i32 0)
+
+  ; CHECK-NEXT: store{{.*}}__dfsan_retval_tls
+  ; CHECK_ORIGIN-NEXT: store{{.*}}__dfsan_retval_origin_tls
+  ; CHECK-NEXT: ret i32
+  ret i32 %r
+}
+
+declare i32* @mismatching_callee(i32)
+
+; CHECK-LABEL: define i8* @"dfs$mismatching_musttail_call"
+define i8* @mismatching_musttail_call(i32) {
+  %r = musttail call i32* @mismatching_callee(i32 %0)
+  ; CHECK: musttail call i32* @"dfs$mismatching_callee"
+  ; COMM: No instrumentation between call and ret.
+  ; CHECK-NEXT: bitcast i32* {{.*}} to i8*
+  %c = bitcast i32* %r to i8*
+  ; CHECK-NEXT: ret i8*
+  ret i8* %c
+}