diff --git a/include/llvm/Analysis/BranchProbabilityInfo.h b/include/llvm/Analysis/BranchProbabilityInfo.h
index 02ead98321f..a2c12ab9e82 100644
--- a/include/llvm/Analysis/BranchProbabilityInfo.h
+++ b/include/llvm/Analysis/BranchProbabilityInfo.h
@@ -33,12 +33,12 @@ class BranchProbabilityInfo : public FunctionPass {
   // weight to just "inherit" the non-zero weight of an adjacent successor.
   static const uint32_t DEFAULT_WEIGHT = 16;
 
-  typedef std::pair<BasicBlock *, BasicBlock *> Edge;
+  typedef std::pair<const BasicBlock *, const BasicBlock *> Edge;
 
   DenseMap<Edge, uint32_t> Weights;
 
   // Get sum of the block successors' weights.
-  uint32_t getSumForBlock(BasicBlock *BB) const;
+  uint32_t getSumForBlock(const BasicBlock *BB) const;
 
 public:
   static char ID;
@@ -53,13 +53,14 @@ public:
 
   // Returned value is between 1 and UINT32_MAX. Look at
   // BranchProbabilityInfo.cpp for details.
-  uint32_t getEdgeWeight(BasicBlock *Src, BasicBlock *Dst) const;
+  uint32_t getEdgeWeight(const BasicBlock *Src, const BasicBlock *Dst) const;
 
   // Look at BranchProbabilityInfo.cpp for details. Use it with caution!
-  void setEdgeWeight(BasicBlock *Src, BasicBlock *Dst, uint32_t Weight);
+  void setEdgeWeight(const BasicBlock *Src, const BasicBlock *Dst,
+                     uint32_t Weight);
 
   // A 'Hot' edge is an edge which probability is >= 80%.
-  bool isEdgeHot(BasicBlock *Src, BasicBlock *Dst) const;
+  bool isEdgeHot(const BasicBlock *Src, const BasicBlock *Dst) const;
 
   // Return a hot successor for the block BB or null if there isn't one.
   BasicBlock *getHotSucc(BasicBlock *BB) const;
@@ -67,7 +68,8 @@ public:
   // Return a probability as a fraction between 0 (0% probability) and
   // 1 (100% probability), however the value is never equal to 0, and can be 1
   // only iff SRC block has only one successor.
-  BranchProbability getEdgeProbability(BasicBlock *Src, BasicBlock *Dst) const;
+  BranchProbability getEdgeProbability(const BasicBlock *Src,
+                                       const BasicBlock *Dst) const;
 
   // Print value between 0 (0% probability) and 1 (100% probability),
   // however the value is never equal to 0, and can be 1 only iff SRC block
diff --git a/lib/Analysis/BranchProbabilityInfo.cpp b/lib/Analysis/BranchProbabilityInfo.cpp
index bdea338f21d..c52a0614f04 100644
--- a/lib/Analysis/BranchProbabilityInfo.cpp
+++ b/lib/Analysis/BranchProbabilityInfo.cpp
@@ -33,7 +33,7 @@ namespace {
 // private methods are hidden in the .cpp file.
 class BranchProbabilityAnalysis {
 
-  typedef std::pair<BasicBlock *, BasicBlock *> Edge;
+  typedef std::pair<const BasicBlock *, const BasicBlock *> Edge;
 
   DenseMap<Edge, uint32_t> *Weights;
 
@@ -301,11 +301,11 @@ bool BranchProbabilityInfo::runOnFunction(Function &F) {
   return BPA.runOnFunction(F);
 }
 
-uint32_t BranchProbabilityInfo::getSumForBlock(BasicBlock *BB) const {
+uint32_t BranchProbabilityInfo::getSumForBlock(const BasicBlock *BB) const {
   uint32_t Sum = 0;
 
-  for (succ_iterator I = succ_begin(BB), E = succ_end(BB); I != E; ++I) {
-    BasicBlock *Succ = *I;
+  for (succ_const_iterator I = succ_begin(BB), E = succ_end(BB); I != E; ++I) {
+    const BasicBlock *Succ = *I;
     uint32_t Weight = getEdgeWeight(BB, Succ);
     uint32_t PrevSum = Sum;
 
@@ -316,7 +316,8 @@ uint32_t BranchProbabilityInfo::getSumForBlock(BasicBlock *BB) const {
   return Sum;
 }
 
-bool BranchProbabilityInfo::isEdgeHot(BasicBlock *Src, BasicBlock *Dst) const {
+bool BranchProbabilityInfo::
+isEdgeHot(const BasicBlock *Src, const BasicBlock *Dst) const {
   // Hot probability is at least 4/5 = 80%
   uint32_t Weight = getEdgeWeight(Src, Dst);
   uint32_t Sum = getSumForBlock(Src);
@@ -353,8 +354,8 @@ BasicBlock *BranchProbabilityInfo::getHotSucc(BasicBlock *BB) const {
 }
 
 // Return edge's weight. If can't find it, return DEFAULT_WEIGHT value.
-uint32_t
-BranchProbabilityInfo::getEdgeWeight(BasicBlock *Src, BasicBlock *Dst) const {
+uint32_t BranchProbabilityInfo::
+getEdgeWeight(const BasicBlock *Src, const BasicBlock *Dst) const {
   Edge E(Src, Dst);
   DenseMap<Edge, uint32_t>::const_iterator I = Weights.find(E);
 
@@ -364,8 +365,8 @@ BranchProbabilityInfo::getEdgeWeight(BasicBlock *Src, BasicBlock *Dst) const {
   return DEFAULT_WEIGHT;
 }
 
-void BranchProbabilityInfo::setEdgeWeight(BasicBlock *Src, BasicBlock *Dst,
-                                     uint32_t Weight) {
+void BranchProbabilityInfo::
+setEdgeWeight(const BasicBlock *Src, const BasicBlock *Dst, uint32_t Weight) {
   Weights[std::make_pair(Src, Dst)] = Weight;
   DEBUG(dbgs() << "set edge " << Src->getNameStr() << " -> "
                << Dst->getNameStr() << " weight to " << Weight
@@ -374,7 +375,7 @@ void BranchProbabilityInfo::setEdgeWeight(BasicBlock *Src, BasicBlock *Dst,
 
 
 BranchProbability BranchProbabilityInfo::
-getEdgeProbability(BasicBlock *Src, BasicBlock *Dst) const {
+getEdgeProbability(const BasicBlock *Src, const BasicBlock *Dst) const {
 
   uint32_t N = getEdgeWeight(Src, Dst);
   uint32_t D = getSumForBlock(Src);