diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index c775c38..15330c2 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -2424,7 +2424,8 @@
            ME = DbgValues.end(); MI != ME; ++MI) {
       const MDNode *Var =
         (*MI)->getOperand((*MI)->getNumOperands()-1).getMetadata();
-      if (Var == DV && !PrevMI->isIdenticalTo(*MI))
+      if (Var == DV && 
+          !PrevMI->isIdenticalTo(*MI))
         MultipleValues.push_back(*MI);
       PrevMI = *MI;
     }
@@ -2447,7 +2448,7 @@
       DbgVariableToDbgInstMap[AbsVar] = MInsn;
       VarToAbstractVarMap[RegVar] = AbsVar;
     }
-    if (MultipleValues.size() <= 1 && !RegClobberInsn.count(MInsn)) {
+    if (MultipleValues.size() <= 1) {
       DbgVariableToDbgInstMap[RegVar] = MInsn;
       continue;
     }
@@ -2457,11 +2458,16 @@
       RegVar->setDotDebugLocOffset(0);
     else
       RegVar->setDotDebugLocOffset(DotDebugLocEntries.size());
-
+    const MachineInstr *Begin = NULL;
+    const MachineInstr *End = NULL;
     for (SmallVector<const MachineInstr *, 4>::iterator
            MVI = MultipleValues.begin(), MVE = MultipleValues.end();
          MVI != MVE; ++MVI) {
-      const MachineInstr *Begin = *MVI;
+      if (!Begin) {
+        Begin = *MVI;
+        continue;
+      }
+      End = *MVI;
       MachineLocation MLoc;
       if (Begin->getNumOperands() == 3) {
         if (Begin->getOperand(0).isReg() && Begin->getOperand(1).isImm())
@@ -2469,25 +2475,25 @@
       } else
         MLoc = Asm->getDebugValueLocation(Begin);
 
-      if (!MLoc.getReg())
-        continue;
-
-      // Compute the range for a register location.
       const MCSymbol *FLabel = getLabelBeforeInsn(Begin);
-      const MCSymbol *SLabel = 0;
+      const MCSymbol *SLabel = getLabelBeforeInsn(End);
+      if (MLoc.getReg())
+        DotDebugLocEntries.push_back(DotDebugLocEntry(FLabel, SLabel, MLoc));
 
-      if (const MachineInstr *ClobberMI = RegClobberInsn.lookup(Begin))
-        // The register range starting at Begin may be clobbered.
-        SLabel = getLabelAfterInsn(ClobberMI);
-      else if (MVI + 1 == MVE)
-        // If Begin is the last instruction then its value is valid
+      Begin = End;
+      if (MVI + 1 == MVE) {
+        // If End is the last instruction then its value is valid
         // until the end of the funtion.
-        SLabel = FunctionEndSym;
-      else
-        // The value is valid until the next DBG_VALUE.
-        SLabel = getLabelBeforeInsn(MVI[1]);
-
-      DotDebugLocEntries.push_back(DotDebugLocEntry(FLabel, SLabel, MLoc));
+        MachineLocation EMLoc;
+        if (End->getNumOperands() == 3) {
+          if (End->getOperand(0).isReg() && Begin->getOperand(1).isImm())
+          EMLoc.set(Begin->getOperand(0).getReg(), Begin->getOperand(1).getImm());
+        } else
+          EMLoc = Asm->getDebugValueLocation(End);
+        if (EMLoc.getReg()) 
+          DotDebugLocEntries.
+            push_back(DotDebugLocEntry(SLabel, FunctionEndSym, EMLoc));
+      }
     }
     DotDebugLocEntries.push_back(DotDebugLocEntry());
   }
@@ -2562,7 +2568,7 @@
 
 /// endInstruction - Process end of an instruction.
 void DwarfDebug::endInstruction(const MachineInstr *MI) {
-  if (InsnsNeedsLabelAfter.count(MI) != 0) {
+  if (InsnsEndScopeSet.count(MI) != 0) {
     // Emit a label if this instruction ends a scope.
     MCSymbol *Label = MMI->getContext().CreateTempSymbol();
     Asm->OutStreamer.EmitLabel(Label);
@@ -2827,7 +2833,7 @@
            RE = Ranges.end(); RI != RE; ++RI) {
       assert(RI->first && "DbgRange does not have first instruction!");
       assert(RI->second && "DbgRange does not have second instruction!");
-      InsnsNeedsLabelAfter.insert(RI->second);
+      InsnsEndScopeSet.insert(RI->second);
     }
   }
 }
@@ -2908,14 +2914,6 @@
   /// ProcessedArgs - Collection of arguments already processed.
   SmallPtrSet<const MDNode *, 8> ProcessedArgs;
 
-  /// LastDbgValue - Refer back to the last DBG_VALUE instruction to mention MD.
-  DenseMap<const MDNode*, const MachineInstr*> LastDbgValue;
-
-  const TargetRegisterInfo *TRI = Asm->TM.getRegisterInfo();
-
-  /// LiveUserVar - Map physreg numbers to the MDNode they contain.
-  std::vector<const MDNode*> LiveUserVar(TRI->getNumRegs());
-
   DebugLoc PrevLoc;
   for (MachineFunction::const_iterator I = MF->begin(), E = MF->end();
        I != E; ++I)
@@ -2925,15 +2923,7 @@
       DebugLoc DL = MI->getDebugLoc();
       if (MI->isDebugValue()) {
         assert (MI->getNumOperands() > 1 && "Invalid machine instruction!");
-
-        // Keep track of variables in registers.
-        const MDNode *Var =
-          MI->getOperand(MI->getNumOperands() - 1).getMetadata();
-        LastDbgValue[Var] = MI;
-        if (isDbgValueInDefinedReg(MI))
-          LiveUserVar[MI->getOperand(0).getReg()] = Var;
-
-        DIVariable DV(Var);
+        DIVariable DV(MI->getOperand(MI->getNumOperands() - 1).getMetadata());
         if (!DV.Verify()) continue;
         // If DBG_VALUE is for a local variable then it needs a label.
         if (DV.getTag() != dwarf::DW_TAG_arg_variable)
@@ -2954,32 +2944,6 @@
         } else if (DL != PrevLoc)
           // Otherwise, instruction needs a location only if it is new location.
           InsnNeedsLabel.insert(MI);
-
-        // Check if the instruction clobbers any registers with debug vars.
-        for (MachineInstr::const_mop_iterator MOI = MI->operands_begin(),
-               MOE = MI->operands_end(); MOI != MOE; ++MOI) {
-          if (!MOI->isReg() || !MOI->isDef() || !MOI->getReg())
-            continue;
-          for (const unsigned *AI = TRI->getOverlaps(MOI->getReg());
-               unsigned Reg = *AI; ++AI) {
-            const MDNode *Var = LiveUserVar[Reg];
-            if (!Var)
-              continue;
-            // Reg is now clobbered.
-            LiveUserVar[Reg] = 0;
-
-            // Was MD last defined by a DBG_VALUE referring to Reg?
-            const MachineInstr *Last = LastDbgValue.lookup(Var);
-            if (!Last || Last->getParent() != MI->getParent())
-              continue;
-            if (!isDbgValueInDefinedReg(Last) ||
-                Last->getOperand(0).getReg() != Reg)
-              continue;
-            // MD is clobbered. Make sure the next instruction gets a label.
-            InsnsNeedsLabelAfter.insert(MI);
-            RegClobberInsn[Last] = MI;
-          }
-        }
       }
 
       if (!DL.isUnknown() || UnknownLocations)
@@ -3049,8 +3013,7 @@
   VarToAbstractVarMap.clear();
   DbgVariableToDbgInstMap.clear();
   DeleteContainerSeconds(DbgScopeMap);
-  InsnsNeedsLabelAfter.clear();
-  RegClobberInsn.clear();
+  InsnsEndScopeSet.clear();
   ConcreteScopes.clear();
   DeleteContainerSeconds(AbstractScopes);
   AbstractScopesList.clear();
diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.h b/lib/CodeGen/AsmPrinter/DwarfDebug.h
index e59ab5b..2863ea3 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -200,6 +200,8 @@
 
   typedef SmallVector<DbgScope *, 2> ScopeVector;
 
+  SmallPtrSet<const MachineInstr *, 8> InsnsEndScopeSet;
+
   /// InlineInfo - Keep track of inlined functions and their location.  This
   /// information is used to populate debug_inlined section.
   typedef std::pair<const MCSymbol *, DIE *> InlineInfoLabels;
@@ -222,16 +224,6 @@
   /// a debuggging information entity.
   SmallPtrSet<const MachineInstr *, 8> InsnNeedsLabel;
 
-  /// InsnsNeedsLabelAfter - Collection of instructions that need a label after
-  /// the instruction because they end a scope of clobber a register.
-  SmallPtrSet<const MachineInstr *, 8> InsnsNeedsLabelAfter;
-
-  /// RegClobberInsn - For each DBG_VALUE instruction referring to a register
-  /// that is clobbered before the variable gets a new DBG_VALUE, map the
-  /// instruction that clobbered the register. This instruction will also be in
-  /// InsnsNeedsLabelAfter.
-  DenseMap<const MachineInstr *, const MachineInstr *> RegClobberInsn;
-
   SmallVector<const MCSymbol *, 8> DebugRangeSymbols;
 
   /// Previous instruction's location information. This is used to determine
diff --git a/lib/CodeGen/LiveDebugVariables.cpp b/lib/CodeGen/LiveDebugVariables.cpp
index 900dc01..20e997a 100644
--- a/lib/CodeGen/LiveDebugVariables.cpp
+++ b/lib/CodeGen/LiveDebugVariables.cpp
@@ -101,6 +101,10 @@
   void insertDebugValue(MachineBasicBlock *MBB, SlotIndex Idx, unsigned LocNo,
                         LiveIntervals &LIS, const TargetInstrInfo &TII);
 
+  /// insertDebugKill - Insert an undef DBG_VALUE into MBB at Idx.
+  void insertDebugKill(MachineBasicBlock *MBB, SlotIndex Idx,
+                       LiveIntervals &LIS, const TargetInstrInfo &TII);
+
 public:
   /// UserValue - Create a new UserValue.
   UserValue(const MDNode *var, unsigned o, DebugLoc L, 
@@ -748,6 +752,13 @@
     .addOperand(Loc).addImm(offset).addMetadata(variable);
 }
 
+void UserValue::insertDebugKill(MachineBasicBlock *MBB, SlotIndex Idx,
+                               LiveIntervals &LIS, const TargetInstrInfo &TII) {
+  MachineBasicBlock::iterator I = findInsertLocation(MBB, Idx, LIS);
+  BuildMI(*MBB, I, findDebugLoc(), TII.get(TargetOpcode::DBG_VALUE)).addReg(0)
+    .addImm(offset).addMetadata(variable);
+}
+
 void UserValue::emitDebugValues(VirtRegMap *VRM, LiveIntervals &LIS,
                                 const TargetInstrInfo &TII) {
   MachineFunction::iterator MFEnd = VRM->getMachineFunction().end();
@@ -779,6 +790,12 @@
       break;
 
     ++I;
+    if (Stop == MBBEnd)
+      continue;
+    // The current interval ends before MBB.
+    // Insert a kill if there is a gap.
+    if (!I.valid() || I.start() > Stop)
+      insertDebugKill(MBB, Stop, LIS, TII);
   }
 }