Index: lib/CodeGen/SelectionDAG/InstrEmitter.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/InstrEmitter.cpp
+++ lib/CodeGen/SelectionDAG/InstrEmitter.cpp
@@ -694,6 +694,20 @@
   assert(cast<DILocalVariable>(Var)->isValidLocationForIntrinsic(DL) &&
          "Expected inlined-at fields to agree");
 
+  SD->setIsEmitted();
+
+  if (SD->isInvalidated()) {
+    // An invalidated SDNode must generate an undef DBG_VALUE: although the
+    // original value is no longer computed, earlier DBG_VALUEs live ranges
+    // must be prevented from leaking into later code.
+    auto MIB = BuildMI(*MF, DL, TII->get(TargetOpcode::DBG_VALUE));
+    MIB.addReg(0U);
+    MIB.addReg(0U, RegState::Debug);
+    MIB.addMetadata(Var);
+    MIB.addMetadata(Expr);
+    return &*MIB;
+  }
+
   if (SD->getKind() == SDDbgValue::FRAMEIX) {
     // Stack address; this needs to be lowered in target-dependent fashion.
     // EmitTargetCodeForFrameDebugValue is responsible for allocation.
Index: lib/CodeGen/SelectionDAG/SDNodeDbgValue.h
===================================================================
--- lib/CodeGen/SelectionDAG/SDNodeDbgValue.h
+++ lib/CodeGen/SelectionDAG/SDNodeDbgValue.h
@@ -53,6 +53,7 @@
   enum DbgValueKind kind;
   bool IsIndirect;
   bool Invalid = false;
+  bool Emitted = false;
 
 public:
   /// Constructor for non-constants.
@@ -126,6 +127,15 @@
   void setIsInvalidated() { Invalid = true; }
   bool isInvalidated() const { return Invalid; }
 
+  /// setIsEmitted / isEmitted - Getter/Setter for flag indicating that this
+  /// SDDbgValue has been emitted to an MBB.
+  void setIsEmitted() { Emitted = true; }
+  bool isEmitted() const { return Emitted; }
+
+  /// clearIsEmitted - Reset Emitted flag, for certain special cases where
+  /// dbg.addr is emitted twice.
+  void clearIsEmitted() { Emitted = false; }
+
   LLVM_DUMP_METHOD void dump(raw_ostream &OS) const;
 };
 
Index: lib/CodeGen/SelectionDAG/ScheduleDAGFast.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/ScheduleDAGFast.cpp
+++ lib/CodeGen/SelectionDAG/ScheduleDAGFast.cpp
@@ -776,11 +776,9 @@
     if (N->getHasDebugValue()) {
       MachineBasicBlock::iterator InsertPos = Emitter.getInsertPos();
       for (auto DV : DAG->GetDbgValues(N)) {
-        if (DV->isInvalidated())
-          continue;
-        if (auto *DbgMI = Emitter.EmitDbgValue(DV, VRBaseMap))
-          BB->insert(InsertPos, DbgMI);
-        DV->setIsInvalidated();
+        if (!DV->isEmitted())
+          if (auto *DbgMI = Emitter.EmitDbgValue(DV, VRBaseMap))
+            BB->insert(InsertPos, DbgMI);
       }
     }
   }
Index: lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.cpp
+++ lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.cpp
@@ -722,7 +722,7 @@
   MachineBasicBlock *BB = Emitter.getBlock();
   MachineBasicBlock::iterator InsertPos = Emitter.getInsertPos();
   for (auto DV : DAG->GetDbgValues(N)) {
-    if (DV->isInvalidated())
+    if (DV->isEmitted())
       continue;
     unsigned DVOrder = DV->getOrder();
     if (!Order || DVOrder == Order) {
@@ -731,7 +731,6 @@
         Orders.push_back({DVOrder, DbgMI});
         BB->insert(InsertPos, DbgMI);
       }
-      DV->setIsInvalidated();
     }
   }
 }
@@ -822,8 +821,10 @@
     SDDbgInfo::DbgIterator PDE = DAG->ByvalParmDbgEnd();
     for (; PDI != PDE; ++PDI) {
       MachineInstr *DbgMI= Emitter.EmitDbgValue(*PDI, VRBaseMap);
-      if (DbgMI)
+      if (DbgMI) {
         BB->insert(InsertPos, DbgMI);
+        (*PDI)->clearIsEmitted();
+      }
     }
   }
 
@@ -889,7 +890,7 @@
       for (; DI != DE; ++DI) {
         if ((*DI)->getOrder() < LastOrder || (*DI)->getOrder() >= Order)
           break;
-        if ((*DI)->isInvalidated())
+        if ((*DI)->isEmitted())
           continue;
 
         MachineInstr *DbgMI = Emitter.EmitDbgValue(*DI, VRBaseMap);
@@ -911,7 +912,7 @@
     // some of them before one or more conditional branches?
     SmallVector<MachineInstr*, 8> DbgMIs;
     for (; DI != DE; ++DI) {
-      if ((*DI)->isInvalidated())
+      if ((*DI)->isEmitted())
         continue;
       assert((*DI)->getOrder() >= LastOrder &&
              "emitting DBG_VALUE out of order");
Index: lib/CodeGen/SelectionDAG/SelectionDAG.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -7742,8 +7742,10 @@
                     Dbg->getDebugLoc(), Dbg->getOrder());
     ClonedDVs.push_back(Clone);
 
-    if (InvalidateDbg)
+    if (InvalidateDbg) {
       Dbg->setIsInvalidated();
+      Dbg->setIsEmitted();
+    }
   }
 
   for (SDDbgValue *Dbg : ClonedDVs)
@@ -7780,6 +7782,7 @@
                         DV->isIndirect(), DV->getDebugLoc(), DV->getOrder());
         ClonedDVs.push_back(Clone);
         DV->setIsInvalidated();
+        DV->setIsEmitted();
         LLVM_DEBUG(dbgs() << "SALVAGE: Rewriting";
                    N0.getNode()->dumprFull(this);
                    dbgs() << " into " << *DIExpr << '\n');