diff --git a/include/llvm/DebugInfo.h b/include/llvm/DebugInfo.h
index dae03ad..66d91b5 100644
--- a/include/llvm/DebugInfo.h
+++ b/include/llvm/DebugInfo.h
@@ -836,7 +836,7 @@
   public:
     /// processModule - Process entire module and collect debug info
     /// anchors.
-    void processModule(Module &M);
+    void processModule(const Module &M);
 
   private:
     /// processType - Process DIType.
@@ -849,7 +849,7 @@
     void processSubprogram(DISubprogram SP);
 
     /// processDeclare - Process DbgDeclareInst.
-    void processDeclare(DbgDeclareInst *DDI);
+    void processDeclare(const DbgDeclareInst *DDI);
 
     /// processLocation - Process DILocation.
     void processLocation(DILocation Loc);
diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index cb61ac3..f625027 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -190,7 +190,7 @@
 
   {
     NamedRegionTimer T(DbgTimerName, DWARFGroupName, TimePassesIsEnabled);
-    beginModule(M);
+    beginModule();
   }
 }
 DwarfDebug::~DwarfDebug() {
@@ -684,7 +684,7 @@
 
 /// collectInfoFromNamedMDNodes - Collect debug info from named mdnodes such
 /// as llvm.dbg.enum and llvm.dbg.ty
-void DwarfDebug::collectInfoFromNamedMDNodes(Module *M) {
+void DwarfDebug::collectInfoFromNamedMDNodes(const Module *M) {
   if (NamedMDNode *NMD = M->getNamedMetadata("llvm.dbg.sp"))
     for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i) {
       const MDNode *N = NMD->getOperand(i);
@@ -716,7 +716,7 @@
 
 /// collectLegacyDebugInfo - Collect debug info using DebugInfoFinder.
 /// FIXME - Remove this when dragon-egg and llvm-gcc switch to DIBuilder.
-bool DwarfDebug::collectLegacyDebugInfo(Module *M) {
+bool DwarfDebug::collectLegacyDebugInfo(const Module *M) {
   DebugInfoFinder DbgFinder;
   DbgFinder.processModule(*M);
 
@@ -759,10 +759,12 @@
 /// beginModule - Emit all Dwarf sections that should come prior to the
 /// content. Create global DIEs and emit initial debug info sections.
 /// This is invoked by the target AsmPrinter.
-void DwarfDebug::beginModule(Module *M) {
+void DwarfDebug::beginModule() {
   if (DisableDebugInfoPrinting)
     return;
 
+  const Module *M = MMI->getModule();
+
   // If module has named metadata anchors then use them, otherwise scan the
   // module using debug info finder to collect debug info.
   NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu");
@@ -798,7 +800,9 @@
 /// endModule - Emit all Dwarf sections that should come after the content.
 ///
 void DwarfDebug::endModule() {
+
   if (!FirstCU) return;
+
   const Module *M = MMI->getModule();
   DenseMap<const MDNode *, LexicalScope *> DeadFnScopeMap;
 
diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.h b/lib/CodeGen/AsmPrinter/DwarfDebug.h
index 1188ffa..5b281fe 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -494,15 +494,15 @@
 
   /// collectInfoFromNamedMDNodes - Collect debug info from named mdnodes such
   /// as llvm.dbg.enum and llvm.dbg.ty
-  void collectInfoFromNamedMDNodes(Module *M);
+  void collectInfoFromNamedMDNodes(const Module *M);
 
   /// collectLegacyDebugInfo - Collect debug info using DebugInfoFinder.
   /// FIXME - Remove this when DragonEgg switches to DIBuilder.
-  bool collectLegacyDebugInfo(Module *M);
+  bool collectLegacyDebugInfo(const Module *M);
 
   /// beginModule - Emit all Dwarf sections that should come prior to the
   /// content.
-  void beginModule(Module *M);
+  void beginModule();
 
   /// endModule - Emit all Dwarf sections that should come after the content.
   ///
diff --git a/lib/VMCore/DebugInfo.cpp b/lib/VMCore/DebugInfo.cpp
index 3029ce2..574d2fe 100644
--- a/lib/VMCore/DebugInfo.cpp
+++ b/lib/VMCore/DebugInfo.cpp
@@ -793,7 +793,7 @@
 //===----------------------------------------------------------------------===//
 
 /// processModule - Process entire module and collect debug info.
-void DebugInfoFinder::processModule(Module &M) {
+void DebugInfoFinder::processModule(const Module &M) {
   if (NamedMDNode *CU_Nodes = M.getNamedMetadata("llvm.dbg.cu")) {
     for (unsigned i = 0, e = CU_Nodes->getNumOperands(); i != e; ++i) {
       DICompileUnit CU(CU_Nodes->getOperand(i));
@@ -819,11 +819,11 @@
     }
   }
 
-  for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
-    for (Function::iterator FI = (*I).begin(), FE = (*I).end(); FI != FE; ++FI)
-      for (BasicBlock::iterator BI = (*FI).begin(), BE = (*FI).end(); BI != BE;
+  for (Module::const_iterator I = M.begin(), E = M.end(); I != E; ++I)
+    for (Function::const_iterator FI = (*I).begin(), FE = (*I).end(); FI != FE; ++FI)
+      for (BasicBlock::const_iterator BI = (*FI).begin(), BE = (*FI).end(); BI != BE;
            ++BI) {
-        if (DbgDeclareInst *DDI = dyn_cast<DbgDeclareInst>(BI))
+        if (const DbgDeclareInst *DDI = dyn_cast<DbgDeclareInst>(BI))
           processDeclare(DDI);
 
         DebugLoc Loc = BI->getDebugLoc();
@@ -927,7 +927,7 @@
 }
 
 /// processDeclare - Process DbgDeclareInst.
-void DebugInfoFinder::processDeclare(DbgDeclareInst *DDI) {
+void DebugInfoFinder::processDeclare(const DbgDeclareInst *DDI) {
   MDNode *N = dyn_cast<MDNode>(DDI->getVariable());
   if (!N) return;