diff --git a/include/llvm/CodeGen/LiveIntervalAnalysis.h b/include/llvm/CodeGen/LiveIntervalAnalysis.h
index 098262aa828..0552d9d06e4 100644
--- a/include/llvm/CodeGen/LiveIntervalAnalysis.h
+++ b/include/llvm/CodeGen/LiveIntervalAnalysis.h
@@ -398,6 +398,10 @@ namespace llvm {
     /// of its subregisters.
     void removePhysRegDefAt(unsigned Reg, SlotIndex Pos);
 
+    /// Remove value number and related live segments of @p LI and its subranges
+    /// that start at position @p Pos.
+    void removeVRegDefAt(LiveInterval &LI, SlotIndex Pos);
+
   private:
     /// Compute live intervals for all virtual registers.
     void computeVirtRegs();
diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp
index 48daf2ccd06..c03773f8037 100644
--- a/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -1375,3 +1375,17 @@ void LiveIntervals::removePhysRegDefAt(unsigned Reg, SlotIndex Pos) {
         LR->removeValNo(VNI);
   }
 }
+
+void LiveIntervals::removeVRegDefAt(LiveInterval &LI, SlotIndex Pos) {
+  VNInfo *VNI = LI.getVNInfoAt(Pos);
+  if (VNI == nullptr)
+    return;
+  LI.removeValNo(VNI);
+
+  // Also remove the value in subranges.
+  for (LiveInterval::SubRange &S : LI.subranges()) {
+    if (VNInfo *SVNI = S.getVNInfoAt(Pos))
+      S.removeValNo(SVNI);
+  }
+  LI.removeEmptySubRanges();
+}
diff --git a/lib/CodeGen/LiveRangeEdit.cpp b/lib/CodeGen/LiveRangeEdit.cpp
index c4bfc0e876c..189da659626 100644
--- a/lib/CodeGen/LiveRangeEdit.cpp
+++ b/lib/CodeGen/LiveRangeEdit.cpp
@@ -273,21 +273,11 @@ void LiveRangeEdit::eliminateDeadDef(MachineInstr *MI, ToShrinkSet &ToShrink) {
 
     // Remove defined value.
     if (MOI->isDef()) {
-      if (VNInfo *VNI = LI.getVNInfoAt(Idx)) {
-        if (TheDelegate)
-          TheDelegate->LRE_WillShrinkVirtReg(LI.reg);
-        LI.removeValNo(VNI);
-        if (LI.empty()) {
-          RegsToErase.push_back(Reg);
-        } else {
-          // Also remove the value in subranges.
-          for (LiveInterval::SubRange &S : LI.subranges()) {
-            if (VNInfo *SVNI = S.getVNInfoAt(Idx))
-              S.removeValNo(SVNI);
-          }
-          LI.removeEmptySubRanges();
-        }
-      }
+      if (TheDelegate && LI.getVNInfoAt(Idx) != nullptr)
+        TheDelegate->LRE_WillShrinkVirtReg(LI.reg);
+      LIS.removeVRegDefAt(LI, Idx);
+      if (LI.empty())
+        RegsToErase.push_back(Reg);
     }
   }
 
diff --git a/lib/CodeGen/RegisterCoalescer.cpp b/lib/CodeGen/RegisterCoalescer.cpp
index 70d2e0e18ce..c136916dc27 100644
--- a/lib/CodeGen/RegisterCoalescer.cpp
+++ b/lib/CodeGen/RegisterCoalescer.cpp
@@ -802,7 +802,6 @@ bool RegisterCoalescer::removeCopyByCommutingDef(const CoalescerPair &CP,
         VNInfo *BSubValNo = NewRange->getNextValue(CopyIdx, Allocator);
         addSegmentsWithValNo(*NewRange, BSubValNo, SA, ASubValNo);
       }
-      SA.removeValNo(ASubValNo);
     }
   }
 
@@ -810,17 +809,8 @@ bool RegisterCoalescer::removeCopyByCommutingDef(const CoalescerPair &CP,
   addSegmentsWithValNo(IntB, BValNo, IntA, AValNo);
   DEBUG(dbgs() << "\t\textended: " << IntB << '\n');
 
-  IntA.removeValNo(AValNo);
-  // Remove valuenos in subranges (the A+B have subranges case has already been
-  // handled above)
-  if (!IntB.hasSubRanges()) {
-    SlotIndex AIdx = CopyIdx.getRegSlot(true);
-    for (LiveInterval::SubRange &SA : IntA.subranges()) {
-      VNInfo *ASubValNo = SA.getVNInfoAt(AIdx);
-      assert(ASubValNo != nullptr);
-      SA.removeValNo(ASubValNo);
-    }
-  }
+  LIS->removeVRegDefAt(IntA, AValNo->def);
+
   DEBUG(dbgs() << "\t\ttrimmed:  " << IntA << '\n');
   ++numCommutes;
   return true;
@@ -1013,13 +1003,6 @@ bool RegisterCoalescer::reMaterializeTrivialDef(CoalescerPair &CP,
   return true;
 }
 
-static void removeUndefValue(LiveRange &LR, SlotIndex At)
-{
-  VNInfo *VNInfo = LR.getVNInfoAt(At);
-  assert(VNInfo != nullptr && SlotIndex::isSameInstr(VNInfo->def, At));
-  LR.removeValNo(VNInfo);
-}
-
 bool RegisterCoalescer::eliminateUndefCopy(MachineInstr *CopyMI) {
   // ProcessImpicitDefs may leave some copies of <undef> values, it only removes
   // local variables. When we have a copy like:
@@ -1053,22 +1036,25 @@ bool RegisterCoalescer::eliminateUndefCopy(MachineInstr *CopyMI) {
 
   // Remove any DstReg segments starting at the instruction.
   LiveInterval &DstLI = LIS->getInterval(DstReg);
-  unsigned DstMask = TRI->getSubRegIndexLaneMask(DstSubIdx);
   SlotIndex RegIndex = Idx.getRegSlot();
-  for (LiveInterval::SubRange &SR : DstLI.subranges()) {
-    if ((SR.LaneMask & DstMask) == 0)
-      continue;
-    removeUndefValue(SR, RegIndex);
-
-    DstLI.removeEmptySubRanges();
-  }
   // Remove value or merge with previous one in case of a subregister def.
   if (VNInfo *PrevVNI = DstLI.getVNInfoAt(Idx)) {
-    VNInfo *VNInfo = DstLI.getVNInfoAt(RegIndex);
-    DstLI.MergeValueNumberInto(VNInfo, PrevVNI);
-  } else {
-    removeUndefValue(DstLI, RegIndex);
-  }
+    VNInfo *VNI = DstLI.getVNInfoAt(RegIndex);
+    DstLI.MergeValueNumberInto(VNI, PrevVNI);
+
+    // The affected subregister segments can be removed.
+    unsigned DstMask = TRI->getSubRegIndexLaneMask(DstSubIdx);
+    for (LiveInterval::SubRange &SR : DstLI.subranges()) {
+      if ((SR.LaneMask & DstMask) == 0)
+        continue;
+
+      VNInfo *SVNI = SR.getVNInfoAt(RegIndex);
+      assert(SVNI != nullptr && SlotIndex::isSameInstr(SVNI->def, RegIndex));
+      SR.removeValNo(SVNI);
+    }
+    DstLI.removeEmptySubRanges();
+  } else
+    LIS->removeVRegDefAt(DstLI, RegIndex);
 
   // Mark uses as undef.
   for (MachineOperand &MO : MRI->reg_nodbg_operands(DstReg)) {
diff --git a/lib/CodeGen/SplitKit.cpp b/lib/CodeGen/SplitKit.cpp
index 4c8801a3611..dab1dfe4f1f 100644
--- a/lib/CodeGen/SplitKit.cpp
+++ b/lib/CodeGen/SplitKit.cpp
@@ -623,8 +623,7 @@ void SplitEditor::removeBackCopies(SmallVectorImpl<VNInfo*> &Copies) {
   AssignI.setMap(RegAssign);
 
   for (unsigned i = 0, e = Copies.size(); i != e; ++i) {
-    VNInfo *VNI = Copies[i];
-    SlotIndex Def = VNI->def;
+    SlotIndex Def = Copies[i]->def;
     MachineInstr *MI = LIS.getInstructionFromIndex(Def);
     assert(MI && "No instruction for back-copy");
 
@@ -635,13 +634,12 @@ void SplitEditor::removeBackCopies(SmallVectorImpl<VNInfo*> &Copies) {
     while (!AtBegin && (--MBBI)->isDebugValue());
 
     DEBUG(dbgs() << "Removing " << Def << '\t' << *MI);
-    LI->removeValNo(VNI);
+    LIS.removeVRegDefAt(*LI, Def);
     LIS.RemoveMachineInstrFromMaps(MI);
     MI->eraseFromParent();
 
-    // Adjust RegAssign if a register assignment is killed at VNI->def.  We
-    // want to avoid calculating the live range of the source register if
-    // possible.
+    // Adjust RegAssign if a register assignment is killed at Def. We want to
+    // avoid calculating the live range of the source register if possible.
     AssignI.find(Def.getPrevSlot());
     if (!AssignI.valid() || AssignI.start() >= Def)
       continue;