diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 9080e34..0a97ef8 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -4294,7 +4294,7 @@
 SDValue SelectionDAG::getMemcpy(SDValue Chain, SDLoc dl, SDValue Dst,
                                 SDValue Src, SDValue Size,
                                 unsigned Align, bool isVol, bool AlwaysInline,
-                                MachinePointerInfo DstPtrInfo,
+                                bool isTailCall, MachinePointerInfo DstPtrInfo,
                                 MachinePointerInfo SrcPtrInfo) {
   assert(Align && "The SDAG layer expects explicit alignment and reserves 0");
 
@@ -4352,15 +4352,16 @@
                Type::getVoidTy(*getContext()),
                getExternalSymbol(TLI->getLibcallName(RTLIB::MEMCPY),
                                  TLI->getPointerTy()), std::move(Args), 0)
-    .setDiscardResult();
-  std::pair<SDValue,SDValue> CallResult = TLI->LowerCallTo(CLI);
+    .setDiscardResult()
+    .setTailCall(isTailCall);
 
+  std::pair<SDValue,SDValue> CallResult = TLI->LowerCallTo(CLI);
   return CallResult.second;
 }
 
 SDValue SelectionDAG::getMemmove(SDValue Chain, SDLoc dl, SDValue Dst,
                                  SDValue Src, SDValue Size,
-                                 unsigned Align, bool isVol,
+                                 unsigned Align, bool isVol, bool isTailCall,
                                  MachinePointerInfo DstPtrInfo,
                                  MachinePointerInfo SrcPtrInfo) {
   assert(Align && "The SDAG layer expects explicit alignment and reserves 0");
@@ -4407,15 +4408,16 @@
                Type::getVoidTy(*getContext()),
                getExternalSymbol(TLI->getLibcallName(RTLIB::MEMMOVE),
                                  TLI->getPointerTy()), std::move(Args), 0)
-    .setDiscardResult();
-  std::pair<SDValue,SDValue> CallResult = TLI->LowerCallTo(CLI);
+    .setDiscardResult()
+    .setTailCall(isTailCall);
 
+  std::pair<SDValue,SDValue> CallResult = TLI->LowerCallTo(CLI);
   return CallResult.second;
 }
 
 SDValue SelectionDAG::getMemset(SDValue Chain, SDLoc dl, SDValue Dst,
                                 SDValue Src, SDValue Size,
-                                unsigned Align, bool isVol,
+                                unsigned Align, bool isVol, bool isTailCall,
                                 MachinePointerInfo DstPtrInfo) {
   assert(Align && "The SDAG layer expects explicit alignment and reserves 0");
 
@@ -4464,7 +4466,8 @@
                Type::getVoidTy(*getContext()),
                getExternalSymbol(TLI->getLibcallName(RTLIB::MEMSET),
                                  TLI->getPointerTy()), std::move(Args), 0)
-    .setDiscardResult();
+    .setDiscardResult()
+    .setTailCall(isTailCall);
 
   std::pair<SDValue,SDValue> CallResult = TLI->LowerCallTo(CLI);
   return CallResult.second;
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 037bcb4..bb0d24a 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -4592,9 +4592,12 @@
     if (!Align)
       Align = 1; // @llvm.memcpy defines 0 and 1 to both mean no alignment.
     bool isVol = cast<ConstantInt>(I.getArgOperand(4))->getZExtValue();
-    DAG.setRoot(DAG.getMemcpy(getRoot(), sdl, Op1, Op2, Op3, Align, isVol, false,
-                              MachinePointerInfo(I.getArgOperand(0)),
-                              MachinePointerInfo(I.getArgOperand(1))));
+    bool isTC = I.isTailCall() && isInTailCallPosition(&I, DAG.getTarget());
+    SDValue MC = DAG.getMemcpy(getRoot(), sdl, Op1, Op2, Op3, Align, isVol,
+                               false, isTC,
+                               MachinePointerInfo(I.getArgOperand(0)),
+                               MachinePointerInfo(I.getArgOperand(1)));
+    updateDAGForMaybeTailCall(MC);
     return nullptr;
   }
   case Intrinsic::memset: {
@@ -4611,8 +4614,10 @@
     if (!Align)
       Align = 1; // @llvm.memset defines 0 and 1 to both mean no alignment.
     bool isVol = cast<ConstantInt>(I.getArgOperand(4))->getZExtValue();
-    DAG.setRoot(DAG.getMemset(getRoot(), sdl, Op1, Op2, Op3, Align, isVol,
-                              MachinePointerInfo(I.getArgOperand(0))));
+    bool isTC = I.isTailCall() && isInTailCallPosition(&I, DAG.getTarget());
+    SDValue MS = DAG.getMemset(getRoot(), sdl, Op1, Op2, Op3, Align, isVol,
+                               isTC, MachinePointerInfo(I.getArgOperand(0)));
+    updateDAGForMaybeTailCall(MS);
     return nullptr;
   }
   case Intrinsic::memmove: {
@@ -4631,9 +4636,11 @@
     if (!Align)
       Align = 1; // @llvm.memmove defines 0 and 1 to both mean no alignment.
     bool isVol = cast<ConstantInt>(I.getArgOperand(4))->getZExtValue();
-    DAG.setRoot(DAG.getMemmove(getRoot(), sdl, Op1, Op2, Op3, Align, isVol,
-                               MachinePointerInfo(I.getArgOperand(0)),
-                               MachinePointerInfo(I.getArgOperand(1))));
+    bool isTC = I.isTailCall() && isInTailCallPosition(&I, DAG.getTarget());
+    SDValue MM = DAG.getMemmove(getRoot(), sdl, Op1, Op2, Op3, Align, isVol,
+                                isTC, MachinePointerInfo(I.getArgOperand(0)),
+                                MachinePointerInfo(I.getArgOperand(1)));
+    updateDAGForMaybeTailCall(MM);
     return nullptr;
   }
   case Intrinsic::dbg_declare: {
@@ -7794,3 +7801,17 @@
     return nullptr;
   return I;
 }
+
+/// During lowering new call nodes can be created (such as memset, etc.).
+/// Those will become new roots of the current DAG, but complications arise
+/// when they are tail calls. In such cases, the call lowering will update
+/// the root, but the builder still needs to know that a tail call has been
+/// lowered in order to avoid generating an additional return.
+void SelectionDAGBuilder::updateDAGForMaybeTailCall(SDValue MaybeTC) {
+  // If the node is null, we do have a tail call.
+  if (MaybeTC.getNode() != nullptr)
+    DAG.setRoot(MaybeTC);
+  else
+    HasTailCall = true;
+}
+
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
index bacb579..a27f470 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
@@ -829,6 +829,10 @@
 
   /// Return the next block after MBB, or nullptr if there is none.
   MachineBasicBlock *NextBlock(MachineBasicBlock *MBB);
+
+  /// Update the DAG and DAG builder with the relevant information after
+  /// a new root node has been created which could be a tail call.
+  void updateDAGForMaybeTailCall(SDValue MaybeTC);
 };
 
 } // end namespace llvm