diff --git a/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp b/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
index fa8257f3834..c5a4860781b 100644
--- a/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
+++ b/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
@@ -234,12 +234,14 @@ class DataFlowSanitizer : public ModulePass {
   FunctionType *DFSanUnimplementedFnTy;
   FunctionType *DFSanSetLabelFnTy;
   FunctionType *DFSanNonzeroLabelFnTy;
+  FunctionType *DFSanVarargWrapperFnTy;
   Constant *DFSanUnionFn;
   Constant *DFSanCheckedUnionFn;
   Constant *DFSanUnionLoadFn;
   Constant *DFSanUnimplementedFn;
   Constant *DFSanSetLabelFn;
   Constant *DFSanNonzeroLabelFn;
+  Constant *DFSanVarargWrapperFn;
   MDNode *ColdCallWeights;
   DFSanABIList ABIList;
   DenseMap<Value *, Function *> UnwrappedFnMap;
@@ -439,6 +441,8 @@ bool DataFlowSanitizer::doInitialization(Module &M) {
                                         DFSanSetLabelArgs, /*isVarArg=*/false);
   DFSanNonzeroLabelFnTy = FunctionType::get(
       Type::getVoidTy(*Ctx), None, /*isVarArg=*/false);
+  DFSanVarargWrapperFnTy = FunctionType::get(
+      Type::getVoidTy(*Ctx), Type::getInt8PtrTy(*Ctx), /*isVarArg=*/false);
 
   if (GetArgTLSPtr) {
     Type *ArgTLSTy = ArrayType::get(ShadowTy, 64);
@@ -518,15 +522,26 @@ DataFlowSanitizer::buildWrapperFunction(Function *F, StringRef NewFName,
                                        AttributeSet::ReturnIndex));
 
   BasicBlock *BB = BasicBlock::Create(*Ctx, "entry", NewF);
-  std::vector<Value *> Args;
-  unsigned n = FT->getNumParams();
-  for (Function::arg_iterator ai = NewF->arg_begin(); n != 0; ++ai, --n)
-    Args.push_back(&*ai);
-  CallInst *CI = CallInst::Create(F, Args, "", BB);
-  if (FT->getReturnType()->isVoidTy())
-    ReturnInst::Create(*Ctx, BB);
-  else
-    ReturnInst::Create(*Ctx, CI, BB);
+  if (F->isVarArg()) {
+    NewF->removeAttributes(
+        AttributeSet::FunctionIndex,
+        AttributeSet().addAttribute(*Ctx, AttributeSet::FunctionIndex,
+                                    "split-stack"));
+    CallInst::Create(DFSanVarargWrapperFn,
+                     IRBuilder<>(BB).CreateGlobalStringPtr(F->getName()), "",
+                     BB);
+    new UnreachableInst(*Ctx, BB);
+  } else {
+    std::vector<Value *> Args;
+    unsigned n = FT->getNumParams();
+    for (Function::arg_iterator ai = NewF->arg_begin(); n != 0; ++ai, --n)
+      Args.push_back(&*ai);
+    CallInst *CI = CallInst::Create(F, Args, "", BB);
+    if (FT->getReturnType()->isVoidTy())
+      ReturnInst::Create(*Ctx, BB);
+    else
+      ReturnInst::Create(*Ctx, CI, BB);
+  }
 
   return NewF;
 }
@@ -617,6 +632,8 @@ bool DataFlowSanitizer::runOnModule(Module &M) {
   }
   DFSanNonzeroLabelFn =
       Mod->getOrInsertFunction("__dfsan_nonzero_label", DFSanNonzeroLabelFnTy);
+  DFSanVarargWrapperFn = Mod->getOrInsertFunction("__dfsan_vararg_wrapper",
+                                                  DFSanVarargWrapperFnTy);
 
   std::vector<Function *> FnsToInstrument;
   llvm::SmallPtrSet<Function *, 2> FnsWithNativeABI;
@@ -627,7 +644,8 @@ bool DataFlowSanitizer::runOnModule(Module &M) {
         i != DFSanUnionLoadFn &&
         i != DFSanUnimplementedFn &&
         i != DFSanSetLabelFn &&
-        i != DFSanNonzeroLabelFn)
+        i != DFSanNonzeroLabelFn &&
+        i != DFSanVarargWrapperFn)
       FnsToInstrument.push_back(&*i);
   }
 
@@ -1363,6 +1381,11 @@ void DFSanVisitor::visitCallSite(CallSite CS) {
     return;
   }
 
+  // Calls to this function are synthesized in wrappers, and we shouldn't
+  // instrument them.
+  if (F == DFSF.DFS.DFSanVarargWrapperFn)
+    return;
+
   assert(!(cast<FunctionType>(
       CS.getCalledValue()->getType()->getPointerElementType())->isVarArg() &&
            dyn_cast<InvokeInst>(CS.getInstruction())));
diff --git a/test/Instrumentation/DataFlowSanitizer/abilist.ll b/test/Instrumentation/DataFlowSanitizer/abilist.ll
index e8cb76d24af..ebf55d9de47 100644
--- a/test/Instrumentation/DataFlowSanitizer/abilist.ll
+++ b/test/Instrumentation/DataFlowSanitizer/abilist.ll
@@ -29,6 +29,9 @@ declare void @custom1(i32 %a, i32 %b)
 ; CHECK: ret { i32, i16 }
 declare i32 @custom2(i32 %a, i32 %b)
 
+; CHECK: define linkonce_odr void @"dfsw$custom3"(i32, i16, i16*, ...)
+; CHECK: call void @__dfsan_vararg_wrapper(i8*
+; CHECK: unreachable
 declare void @custom3(i32 %a, ...)
 
 declare i32 @custom4(i32 %a, ...)
@@ -83,8 +86,6 @@ define i32 (i32, i32)* @g(i32) {
 
 ; CHECK: declare void @__dfsw_custom1(i32, i32, i16, i16)
 ; CHECK: declare i32 @__dfsw_custom2(i32, i32, i16, i16, i16*)
-; CHECK: declare void @__dfsw_custom3(i32, i16, i16*, ...)
-; CHECK: declare i32 @__dfsw_custom4(i32, i16, i16*, i16*, ...)
 
 ; CHECK-LABEL: define linkonce_odr i32 @"dfst0$customcb"(i32 (i32)*, i32, i16, i16*)
 ; CHECK: %[[BC:.*]] = bitcast i32 (i32)* %0 to { i32, i16 } (i32, i16)*
@@ -94,3 +95,5 @@ define i32 (i32, i32)* @g(i32) {
 ; CHECK: store i16 %[[XVAL1]], i16* %3
 ; CHECK: ret i32 %[[XVAL0]]
 
+; CHECK: declare void @__dfsw_custom3(i32, i16, i16*, ...)
+; CHECK: declare i32 @__dfsw_custom4(i32, i16, i16*, i16*, ...)