diff --git a/lib/Transforms/InstCombine/InstCombine.h b/lib/Transforms/InstCombine/InstCombine.h
index d035c53f744..e29bf1aa780 100644
--- a/lib/Transforms/InstCombine/InstCombine.h
+++ b/lib/Transforms/InstCombine/InstCombine.h
@@ -271,7 +271,7 @@ public:
     if (&I == V)
       V = UndefValue::get(I.getType());
 
-    DEBUG(errs() << "IC: Replacing " << I << "\n"
+    DEBUG(dbgs() << "IC: Replacing " << I << "\n"
                     "    with " << *V << '\n');
 
     I.replaceAllUsesWith(V);
@@ -283,7 +283,7 @@ public:
   // instruction.  Instead, visit methods should return the value returned by
   // this function.
   Instruction *EraseInstFromFunction(Instruction &I) {
-    DEBUG(errs() << "IC: ERASE " << I << '\n');
+    DEBUG(dbgs() << "IC: ERASE " << I << '\n');
 
     assert(I.use_empty() && "Cannot erase instruction that is used!");
     // Make sure that we reprocess all operands now that we reduced their
diff --git a/lib/Transforms/InstCombine/InstCombinePHI.cpp b/lib/Transforms/InstCombine/InstCombinePHI.cpp
index bd14e81c3f8..4689c424bc7 100644
--- a/lib/Transforms/InstCombine/InstCombinePHI.cpp
+++ b/lib/Transforms/InstCombine/InstCombinePHI.cpp
@@ -688,10 +688,10 @@ Instruction *InstCombiner::SliceUpIllegalIntegerPHI(PHINode &FirstPhi) {
   // extracted out of it.  First, sort the users by their offset and size.
   array_pod_sort(PHIUsers.begin(), PHIUsers.end());
 
-  DEBUG(errs() << "SLICING UP PHI: " << FirstPhi << '\n';
-            for (unsigned i = 1, e = PHIsToSlice.size(); i != e; ++i)
-              errs() << "AND USER PHI #" << i << ": " << *PHIsToSlice[i] <<'\n';
-        );
+  DEBUG(dbgs() << "SLICING UP PHI: " << FirstPhi << '\n';
+        for (unsigned i = 1, e = PHIsToSlice.size(); i != e; ++i)
+          dbgs() << "AND USER PHI #" << i << ": " << *PHIsToSlice[i] << '\n';
+    );
 
   // PredValues - This is a temporary used when rewriting PHI nodes.  It is
   // hoisted out here to avoid construction/destruction thrashing.
@@ -772,7 +772,7 @@ Instruction *InstCombiner::SliceUpIllegalIntegerPHI(PHINode &FirstPhi) {
       }
       PredValues.clear();
 
-      DEBUG(errs() << "  Made element PHI for offset " << Offset << ": "
+      DEBUG(dbgs() << "  Made element PHI for offset " << Offset << ": "
                    << *EltPHI << '\n');
       ExtractedVals[LoweredPHIRecord(PN, Offset, Ty)] = EltPHI;
     }
diff --git a/lib/Transforms/InstCombine/InstCombineWorklist.h b/lib/Transforms/InstCombine/InstCombineWorklist.h
index 11095585b7b..f84db2730b4 100644
--- a/lib/Transforms/InstCombine/InstCombineWorklist.h
+++ b/lib/Transforms/InstCombine/InstCombineWorklist.h
@@ -37,7 +37,7 @@ public:
   /// in it.
   void Add(Instruction *I) {
     if (WorklistMap.insert(std::make_pair(I, Worklist.size())).second) {
-      DEBUG(errs() << "IC: ADD: " << *I << '\n');
+      DEBUG(dbgs() << "IC: ADD: " << *I << '\n');
       Worklist.push_back(I);
     }
   }
@@ -54,7 +54,7 @@ public:
     assert(Worklist.empty() && "Worklist must be empty to add initial group");
     Worklist.reserve(NumEntries+16);
     WorklistMap.resize(NumEntries);
-    DEBUG(errs() << "IC: ADDING: " << NumEntries << " instrs to worklist\n");
+    DEBUG(dbgs() << "IC: ADDING: " << NumEntries << " instrs to worklist\n");
     for (unsigned Idx = 0; NumEntries; --NumEntries) {
       Instruction *I = List[NumEntries-1];
       WorklistMap.insert(std::make_pair(I, Idx++));
diff --git a/lib/Transforms/InstCombine/InstructionCombining.cpp b/lib/Transforms/InstCombine/InstructionCombining.cpp
index f0a14a36c0c..803c7279bbc 100644
--- a/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -2216,7 +2216,7 @@ static bool AddReachableCodeToWorklist(BasicBlock *BB,
       // DCE instruction if trivially dead.
       if (isInstructionTriviallyDead(Inst, TLI)) {
         ++NumDeadInst;
-        DEBUG(errs() << "IC: DCE: " << *Inst << '\n');
+        DEBUG(dbgs() << "IC: DCE: " << *Inst << '\n');
         Inst->eraseFromParent();
         continue;
       }
@@ -2224,7 +2224,7 @@ static bool AddReachableCodeToWorklist(BasicBlock *BB,
       // ConstantProp instruction if trivially constant.
       if (!Inst->use_empty() && isa<Constant>(Inst->getOperand(0)))
         if (Constant *C = ConstantFoldInstruction(Inst, TD, TLI)) {
-          DEBUG(errs() << "IC: ConstFold to: " << *C << " from: "
+          DEBUG(dbgs() << "IC: ConstFold to: " << *C << " from: "
                        << *Inst << '\n');
           Inst->replaceAllUsesWith(C);
           ++NumConstProp;
@@ -2300,7 +2300,7 @@ static bool AddReachableCodeToWorklist(BasicBlock *BB,
 bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) {
   MadeIRChange = false;
 
-  DEBUG(errs() << "\n\nINSTCOMBINE ITERATION #" << Iteration << " on "
+  DEBUG(dbgs() << "\n\nINSTCOMBINE ITERATION #" << Iteration << " on "
                << F.getName() << "\n");
 
   {
@@ -2345,7 +2345,7 @@ bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) {
 
     // Check to see if we can DCE the instruction.
     if (isInstructionTriviallyDead(I, TLI)) {
-      DEBUG(errs() << "IC: DCE: " << *I << '\n');
+      DEBUG(dbgs() << "IC: DCE: " << *I << '\n');
       EraseInstFromFunction(*I);
       ++NumDeadInst;
       MadeIRChange = true;
@@ -2355,7 +2355,7 @@ bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) {
     // Instruction isn't dead, see if we can constant propagate it.
     if (!I->use_empty() && isa<Constant>(I->getOperand(0)))
       if (Constant *C = ConstantFoldInstruction(I, TD, TLI)) {
-        DEBUG(errs() << "IC: ConstFold to: " << *C << " from: " << *I << '\n');
+        DEBUG(dbgs() << "IC: ConstFold to: " << *C << " from: " << *I << '\n');
 
         // Add operands to the worklist.
         ReplaceInstUsesWith(*I, C);
@@ -2403,13 +2403,13 @@ bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) {
     std::string OrigI;
 #endif
     DEBUG(raw_string_ostream SS(OrigI); I->print(SS); OrigI = SS.str(););
-    DEBUG(errs() << "IC: Visiting: " << OrigI << '\n');
+    DEBUG(dbgs() << "IC: Visiting: " << OrigI << '\n');
 
     if (Instruction *Result = visit(*I)) {
       ++NumCombined;
       // Should we replace the old instruction with a new one?
       if (Result != I) {
-        DEBUG(errs() << "IC: Old = " << *I << '\n'
+        DEBUG(dbgs() << "IC: Old = " << *I << '\n'
                      << "    New = " << *Result << '\n');
 
         if (!I->getDebugLoc().isUnknown())
@@ -2438,7 +2438,7 @@ bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) {
         EraseInstFromFunction(*I);
       } else {
 #ifndef NDEBUG
-        DEBUG(errs() << "IC: Mod = " << OrigI << '\n'
+        DEBUG(dbgs() << "IC: Mod = " << OrigI << '\n'
                      << "    New = " << *I << '\n');
 #endif