diff --git a/lib/CodeGen/DwarfWriter.cpp b/lib/CodeGen/DwarfWriter.cpp
index 81c8963..c8a1333 100644
--- a/lib/CodeGen/DwarfWriter.cpp
+++ b/lib/CodeGen/DwarfWriter.cpp
@@ -1695,15 +1695,18 @@
     return Unit;
   }
 
+  /// GetBaseCompileUnit - Get the main compile unit.
+  ///
+  CompileUnit *GetBaseCompileUnit() const {
+    CompileUnit *Unit = CompileUnits[0];
+    assert(Unit && "Missing compile unit.");
+    return Unit;
+  }
+
   /// FindCompileUnit - Get the compile unit for the given descriptor.
   ///
   CompileUnit *FindCompileUnit(CompileUnitDesc *UnitDesc) {
-#if 1
-    // FIXME - Using only one compile unit.  Needs to me fixed at the FE.
-    CompileUnit *Unit = CompileUnits[0];
-#else
     CompileUnit *Unit = DescToUnitMap[UnitDesc];
-#endif
     assert(Unit && "Missing compile unit.");
     return Unit;
   }
@@ -1859,13 +1862,12 @@
       // FIXME - Ignore inlined functions for the time being.
       if (!Scope->getParent()) continue;
       
-      unsigned StartID = Scope->getStartLabelID();
-      unsigned EndID = Scope->getEndLabelID();
+      unsigned StartID = DebugInfo->MappedLabel(Scope->getStartLabelID());
+      unsigned EndID = DebugInfo->MappedLabel(Scope->getEndLabelID());
       
-      // Widen scope if label is discarded.
-      // FIXME - really need to find a GOOD label if a block is dead.
-      if (StartID && !DebugInfo->isLabelValid(StartID)) StartID = 0;
-      if (EndID && !DebugInfo->isLabelValid(EndID)) EndID = 0;
+      // Ignore empty scopes.
+      if (StartID == EndID && StartID != 0) continue;
+      if (Scope->getScopes().empty() && Scope->getVariables().empty()) continue;
       
       DIE *ScopeDie = new DIE(DW_TAG_lexical_block);
       
@@ -2084,10 +2086,10 @@
                                    std::vector<MachineMove *> &Moves) {
     for (unsigned i = 0, N = Moves.size(); i < N; ++i) {
       MachineMove *Move = Moves[i];
-      unsigned LabelID = Move->getLabelID();
+      unsigned LabelID = DebugInfo->MappedLabel(Move->getLabelID());
       
       // Throw out move if the label is invalid.
-      if (LabelID && !DebugInfo->isLabelValid(LabelID)) continue;
+      if (!LabelID) continue;
       
       const MachineLocation &Dst = Move->getDestination();
       const MachineLocation &Src = Move->getSource();
@@ -2307,9 +2309,8 @@
       // Construct rows of the address, source, line, column matrix.
       for (unsigned i = 0, N = LineInfos.size(); i < N; ++i) {
         const SourceLineInfo &LineInfo = LineInfos[i];
-        unsigned LabelID = LineInfo.getLabelID();
-        
-        // Source line labels are validated at the MachineDebugInfo level.
+        unsigned LabelID = DebugInfo->MappedLabel(LineInfo.getLabelID());
+        if (!LabelID) continue;
         
         if (DwarfVerbose) {
           unsigned SourceID = LineInfo.getSourceID();
@@ -2420,6 +2421,7 @@
   void EmitFunctionDebugFrame() {
     if (!TAI->getDwarfRequiresFrameSection())
       return;
+       
     // Start the dwarf frame section.
     Asm->SwitchToDataSection(TAI->getDwarfFrameSection());
     
@@ -2588,7 +2590,8 @@
     const UniqueVector<CompileUnitDesc *> CUW = DebugInfo->getCompileUnits();
     
     for (unsigned i = 1, N = CUW.size(); i <= N; ++i) {
-      CompileUnit *Unit = NewCompileUnit(CUW[i], i);
+      unsigned ID = DebugInfo->RecordSource(CUW[i]);
+      CompileUnit *Unit = NewCompileUnit(CUW[i], ID);
       CompileUnits.push_back(Unit);
     }
   }
diff --git a/lib/CodeGen/LLVMTargetMachine.cpp b/lib/CodeGen/LLVMTargetMachine.cpp
index b12634a..ae13625 100644
--- a/lib/CodeGen/LLVMTargetMachine.cpp
+++ b/lib/CodeGen/LLVMTargetMachine.cpp
@@ -66,6 +66,9 @@
   // Branch folding must be run after regalloc and prolog/epilog insertion.
   if (!Fast)
     PM.add(createBranchFoldingPass());
+    
+  // Fold redundant debug labels.
+  PM.add(createDebugLabelFoldingPass());
   
   if (PrintMachineCode)  // Print the register-allocated code
     PM.add(createMachineFunctionPrinterPass(&std::cerr));
diff --git a/lib/CodeGen/MachineDebugInfo.cpp b/lib/CodeGen/MachineDebugInfo.cpp
index 490e48d..bdbdd14 100644
--- a/lib/CodeGen/MachineDebugInfo.cpp
+++ b/lib/CodeGen/MachineDebugInfo.cpp
@@ -10,7 +10,11 @@
 #include "llvm/CodeGen/MachineDebugInfo.h"
 
 #include "llvm/Constants.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineLocation.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetMachine.h"
 #include "llvm/DerivedTypes.h"
 #include "llvm/GlobalVariable.h"
 #include "llvm/Intrinsics.h"
@@ -1448,10 +1452,9 @@
 , Directories()
 , SourceFiles()
 , Lines()
-, LabelID(0)
+, LabelIDList()
 , ScopeMap()
 , RootScope(NULL)
-, DeletedLabelIDs()
 , FrameMoves()
 {}
 MachineDebugInfo::~MachineDebugInfo() {
@@ -1544,35 +1547,6 @@
   return ID;
 }
 
-static bool LabelUIDComparison(const SourceLineInfo &LI, unsigned UID) {
-  return LI.getLabelID() < UID;
-}
- 
-/// InvalidateLabel - Inhibit use of the specified label # from
-/// MachineDebugInfo, for example because the code was deleted.
-void MachineDebugInfo::InvalidateLabel(unsigned LabelID) {
-  // Check source line list first.  SourceLineInfo is sorted by LabelID.
-  std::vector<SourceLineInfo>::iterator I =
-    std::lower_bound(Lines.begin(), Lines.end(), LabelID, LabelUIDComparison);
-  if (I != Lines.end() && I->getLabelID() == LabelID) {
-    Lines.erase(I);
-    return;
-  }
-  
-  // Otherwise add for use by isLabelValid.
-  std::vector<unsigned>::iterator J =
-    std::lower_bound(DeletedLabelIDs.begin(), DeletedLabelIDs.end(), LabelID);
-  DeletedLabelIDs.insert(J, LabelID);
-}
-
-/// isLabelValid - Check to make sure the label is still valid before
-/// attempting to use.
-bool MachineDebugInfo::isLabelValid(unsigned LabelID) {
-  std::vector<unsigned>::iterator I =
-    std::lower_bound(DeletedLabelIDs.begin(), DeletedLabelIDs.end(), LabelID);
-  return I == DeletedLabelIDs.end() || *I != LabelID;
-}
-
 /// RecordSource - Register a source file with debug info. Returns an source
 /// ID.
 unsigned MachineDebugInfo::RecordSource(const std::string &Directory,
@@ -1642,4 +1616,70 @@
   return Slot;
 }
 
+//===----------------------------------------------------------------------===//
+/// DebugLabelFolding pass - This pass prunes out redundant debug labels.  This
+/// allows a debug emitter to determine if the range of two labels is empty,
+/// by seeing if the labels map to the same reduced label.
+
+namespace llvm {
+
+struct DebugLabelFolder : public MachineFunctionPass {
+  virtual bool runOnMachineFunction(MachineFunction &MF);
+  virtual const char *getPassName() const { return "Debug Label Folder"; }
+};
+
+bool DebugLabelFolder::runOnMachineFunction(MachineFunction &MF) {
+  // Get machine debug info.
+  MachineDebugInfo *MDI = getAnalysisToUpdate<MachineDebugInfo>();
+  if (!MDI) return false;
+  // Get target instruction info.
+  const TargetInstrInfo *TII = MF.getTarget().getInstrInfo();
+  if (!TII) return false;
+  // Get target version of the debug label opcode.
+  unsigned DWARF_LABELOpc = TII->getDWARF_LABELOpcode();
+  if (!DWARF_LABELOpc) return false;
+  
+  // Track if change is made.
+  bool MadeChange = false;
+  // No prior label to begin.
+  unsigned PriorLabel = 0;
+  
+  // Iterate through basic blocks.
+  for (MachineFunction::iterator BB = MF.begin(), E = MF.end();
+       BB != E; ++BB) {
+    // Iterate through instructions.
+    for (MachineBasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) {
+      // Is it a debug label.
+      if ((unsigned)I->getOpcode() == DWARF_LABELOpc) {
+        // The label ID # is always operand #0, an immediate.
+        unsigned NextLabel = I->getOperand(0).getImm();
+        
+        // If there was an immediate prior label.
+        if (PriorLabel) {
+          // Remap the current label to prior label.
+          MDI->RemapLabel(NextLabel, PriorLabel);
+          // Delete the current label.
+          I = BB->erase(I);
+          // Indicate a change has been made.
+          MadeChange = true;
+          continue;
+        } else {
+          // Start a new round.
+          PriorLabel = NextLabel;
+        }
+       } else {
+        // No consecutive labels.
+        PriorLabel = 0;
+      }
+      
+      ++I;
+    }
+  }
+  
+  return MadeChange;
+}
+
+FunctionPass *createDebugLabelFoldingPass() { return new DebugLabelFolder(); }
+
+}