diff --git a/lib/Transforms/Scalar/GVNPRE.cpp b/lib/Transforms/Scalar/GVNPRE.cpp
new file mode 100644
index 00000000000..41513a086a1
--- /dev/null
+++ b/lib/Transforms/Scalar/GVNPRE.cpp
@@ -0,0 +1,459 @@
+//===- GVNPRE.cpp - Eliminate redundant values and expressions ------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by the Owen Anderson and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass performs a hybrid of global value numbering and partial redundancy
+// elimination, known as GVN-PRE.  It performs partial redundancy elimination on
+// values, rather than lexical expressions, allowing a more comprehensive view 
+// the optimization.  It replaces redundant values with uses of earlier 
+// occurences of the same value.  While this is beneficial in that it eliminates
+// unneeded computation, it also increases register pressure by creating large
+// live ranges, and should be used with caution on platforms that a very 
+// sensitive to register pressure.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "gvnpre"
+#include "llvm/Value.h"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Instructions.h"
+#include "llvm/Function.h"
+#include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/PostDominators.h"
+#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Support/Compiler.h"
+#include <algorithm>
+#include <map>
+#include <set>
+#include <cstdio>
+using namespace llvm;
+
+namespace {
+
+  class VISIBILITY_HIDDEN GVNPRE : public FunctionPass {
+    bool runOnFunction(Function &F);
+  public:
+    static char ID; // Pass identification, replacement for typeid
+    GVNPRE() : FunctionPass((intptr_t)&ID) { nextValueNumber = 0; }
+
+  private:
+    uint32_t nextValueNumber;
+  
+    struct Expression {
+      char opcode;
+      Value* value;
+      uint32_t lhs;
+      uint32_t rhs;
+      
+      bool operator<(const Expression& other) const {
+        if (opcode < other.opcode)
+          return true;
+        else if (other.opcode < opcode)
+          return false;
+        
+        if (opcode == 0) {
+          if (value < other.value)
+            return true;
+          else
+            return false;
+        } else {
+          if (lhs < other.lhs)
+            return true;
+          else if (other.lhs < lhs)
+            return true;
+          else if (rhs < other.rhs)
+            return true;
+          else
+            return false;
+        }
+      }
+      
+      bool operator==(const Expression& other) const {
+        if (opcode != other.opcode)
+          return false;
+        
+        if (value != other.value)
+          return false;
+        
+        if (lhs != other.lhs)
+          return false;
+          
+        if (rhs != other.rhs)
+          return false;
+        
+        return true;
+      }
+    };
+  
+    typedef std::map<Expression, uint32_t> ValueTable;
+  
+    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+      AU.setPreservesCFG();
+      AU.addRequired<DominatorTree>();
+      AU.addRequired<PostDominatorTree>();
+    }
+  
+    // Helper fuctions
+    // FIXME: eliminate or document these better
+    void dump(ValueTable& VN, std::set<Expression>& s);
+    void clean(ValueTable VN, std::set<Expression>& set);
+    Expression add(ValueTable& VN, std::set<Expression>& MS, Instruction* V);
+    ValueTable::iterator lookup(ValueTable& VN, Value* V);
+    Expression buildExpression(ValueTable& VN, Value* V);
+    std::set<Expression>::iterator find_leader(ValueTable VN, 
+                                               std::set<Expression>& vals,
+                                               uint32_t v);
+    void phi_translate(ValueTable& VN, 
+                       std::set<Expression>& anticIn, BasicBlock* B,
+                       std::set<Expression>& out);
+    
+    // For a given block, calculate the generated expressions, temporaries,
+    // and the AVAIL_OUT set
+    void CalculateAvailOut(ValueTable& VN, std::set<Expression>& MS,
+                       DominatorTree::Node* DI,
+                       std::set<Expression>& currExps,
+                       std::set<PHINode*>& currPhis,
+                       std::set<Expression>& currTemps,
+                       std::set<Expression>& currAvail,
+                       std::map<BasicBlock*, std::set<Expression> > availOut);
+  
+  };
+  
+  char GVNPRE::ID = 0;
+  
+}
+
+FunctionPass *llvm::createGVNPREPass() { return new GVNPRE(); }
+
+RegisterPass<GVNPRE> X("gvnpre",
+                       "Global Value Numbering/Partial Redundancy Elimination");
+
+// Given a Value, build an Expression to represent it
+GVNPRE::Expression GVNPRE::buildExpression(ValueTable& VN, Value* V) {
+  if (Instruction* I = dyn_cast<Instruction>(V)) {
+    Expression e;
+    
+    switch (I->getOpcode()) {
+    case 7:
+      e.opcode = 1; // ADD
+      break;
+    case 8:
+      e.opcode = 2; // SUB
+      break;
+    case 9:
+      e.opcode = 3; // MUL
+      break;
+    case 10:
+      e.opcode = 4; // UDIV
+      break;
+    case 11:
+      e.opcode = 5; // SDIV
+      break;
+    case 12:
+      e.opcode = 6; // FDIV
+      break;
+    case 13:
+      e.opcode = 7; // UREM
+      break;
+    case 14:
+      e.opcode = 8; // SREM
+      break;
+    case 15:
+      e.opcode = 9; // FREM
+      break;
+    default:
+     e.opcode = 0; // OPAQUE
+     e.lhs = 0;
+     e.rhs = 0;
+     e.value = V;
+     return e;
+    }
+    
+    e.value = 0;
+    
+    ValueTable::iterator lhs = lookup(VN, I->getOperand(0));
+    if (lhs == VN.end()) {
+      Expression lhsExp = buildExpression(VN, I->getOperand(0));
+      VN.insert(std::make_pair(lhsExp, nextValueNumber));
+      e.lhs = nextValueNumber;
+      nextValueNumber++;
+    } else
+      e.lhs = lhs->second;
+    ValueTable::iterator rhs = lookup(VN, I->getOperand(1));
+    if (rhs == VN.end()) {
+      Expression rhsExp = buildExpression(VN, I->getOperand(1));
+      VN.insert(std::make_pair(rhsExp, nextValueNumber));
+      e.rhs = nextValueNumber;
+      nextValueNumber++;
+    } else
+      e.rhs = rhs->second;
+  
+    return e;
+  } else {
+    Expression e;
+    e.opcode = 0;
+    e.value = V;
+    e.lhs = 0;
+    e.rhs = 0;
+    
+    return e;
+  }
+}
+
+GVNPRE::Expression GVNPRE::add(ValueTable& VN, std::set<Expression>& MS,
+                               Instruction* V) {
+  Expression e = buildExpression(VN, V);
+  if (VN.insert(std::make_pair(e, nextValueNumber)).second)
+    nextValueNumber++;
+  if (e.opcode != 0 || (e.opcode == 0 && isa<PHINode>(e.value)))
+    MS.insert(e);
+  return e;
+}
+
+GVNPRE::ValueTable::iterator GVNPRE::lookup(ValueTable& VN, Value* V) {
+  Expression e = buildExpression(VN, V);
+  return VN.find(e);
+}
+
+std::set<GVNPRE::Expression>::iterator GVNPRE::find_leader(GVNPRE::ValueTable VN,
+                           std::set<GVNPRE::Expression>& vals,
+                           uint32_t v) {
+  for (std::set<Expression>::iterator I = vals.begin(), E = vals.end();
+       I != E; ++I)
+    if (VN[*I] == v)
+      return I;
+  
+  return vals.end();
+}
+
+void GVNPRE::phi_translate(GVNPRE::ValueTable& VN, 
+                           std::set<GVNPRE::Expression>& anticIn, BasicBlock* B,
+                           std::set<GVNPRE::Expression>& out) {
+  BasicBlock* succ = B->getTerminator()->getSuccessor(0);
+  
+  for (std::set<Expression>::iterator I = anticIn.begin(), E = anticIn.end();
+       I != E; ++I) {
+    if (I->opcode == 0) {
+      Value *v = I->value;
+      if (PHINode* p = dyn_cast<PHINode>(v))
+        if (p->getParent() == succ) {
+          out.insert(buildExpression(VN, p->getIncomingValueForBlock(B)));
+          continue;
+        }
+    }
+    //out.insert(*I);
+  }
+}
+
+// Remove all expressions whose operands are not themselves in the set
+void GVNPRE::clean(GVNPRE::ValueTable VN, std::set<GVNPRE::Expression>& set) {
+  unsigned size = set.size();
+  unsigned old = 0;
+  
+  while (size != old) {
+    old = size;
+  
+    std::vector<Expression> worklist(set.begin(), set.end());
+    while (!worklist.empty()) {
+      Expression e = worklist.back();
+      worklist.pop_back();
+    
+      if (e.opcode == 0) // OPAQUE
+        continue;
+      
+      bool lhsValid = false;
+      for (std::set<Expression>::iterator I = set.begin(), E = set.end();
+           I != E; ++I)
+        if (VN[*I] == e.lhs);
+          lhsValid = true;
+          
+      bool rhsValid = false;
+      for (std::set<Expression>::iterator I = set.begin(), E = set.end();
+           I != E; ++I)
+        if (VN[*I] == e.rhs);
+          rhsValid = true;
+      
+      if (!lhsValid || !rhsValid)
+        set.erase(e);
+    }
+    
+    size = set.size();
+  }
+}
+
+void GVNPRE::dump(GVNPRE::ValueTable& VN, std::set<GVNPRE::Expression>& s) {
+  printf("{ ");
+  for (std::set<Expression>::iterator I = s.begin(), E = s.end(); I != E; ++I) {
+    printf("(%d, %s, value.%d, value.%d) ", I->opcode, I->value == 0 ? "0" : I->value->getName().c_str(), I->lhs, I->rhs);
+  }
+  printf("}\n\n");
+}
+
+void GVNPRE::CalculateAvailOut(GVNPRE::ValueTable& VN, std::set<Expression>& MS,
+                       DominatorTree::Node* DI,
+                       std::set<Expression>& currExps,
+                       std::set<PHINode*>& currPhis,
+                       std::set<Expression>& currTemps,
+                       std::set<Expression>& currAvail,
+                       std::map<BasicBlock*, std::set<Expression> > availOut) {
+  
+  BasicBlock* BB = DI->getBlock();
+  
+  // A block inherits AVAIL_OUT from its dominator
+  if (DI->getIDom() != 0)
+  currAvail.insert(availOut[DI->getIDom()->getBlock()].begin(),
+                   availOut[DI->getIDom()->getBlock()].end());
+    
+    
+ for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
+      BI != BE; ++BI) {
+       
+    // Handle PHI nodes...
+    if (PHINode* p = dyn_cast<PHINode>(BI)) {
+      add(VN, MS, p);
+      currPhis.insert(p);
+    
+    // Handle binary ops...
+    } else if (BinaryOperator* BO = dyn_cast<BinaryOperator>(BI)) {
+      Expression leftValue = buildExpression(VN, BO->getOperand(0));
+      Expression rightValue = buildExpression(VN, BO->getOperand(1));
+      
+      Expression e = add(VN, MS, BO);
+      
+      currExps.insert(leftValue);
+      currExps.insert(rightValue);
+      currExps.insert(e);
+      
+      currTemps.insert(e);
+        
+    // Handle unsupported ops
+    } else {
+      Expression e = add(VN, MS, BI);
+      currTemps.insert(e);
+    }
+      
+    currAvail.insert(buildExpression(VN, BI));
+  }
+}
+
+bool GVNPRE::runOnFunction(Function &F) {
+  ValueTable VN;
+  std::set<Expression> maximalSet;
+
+  std::map<BasicBlock*, std::set<Expression> > generatedExpressions;
+  std::map<BasicBlock*, std::set<PHINode*> > generatedPhis;
+  std::map<BasicBlock*, std::set<Expression> > generatedTemporaries;
+  std::map<BasicBlock*, std::set<Expression> > availableOut;
+  std::map<BasicBlock*, std::set<Expression> > anticipatedIn;
+  
+  DominatorTree &DT = getAnalysis<DominatorTree>();   
+  
+  // First Phase of BuildSets - calculate AVAIL_OUT
+  
+  // Top-down walk of the dominator tree
+  for (df_iterator<DominatorTree::Node*> DI = df_begin(DT.getRootNode()),
+         E = df_end(DT.getRootNode()); DI != E; ++DI) {
+    
+    // Get the sets to update for this block
+    std::set<Expression>& currExps = generatedExpressions[DI->getBlock()];
+    std::set<PHINode*>& currPhis = generatedPhis[DI->getBlock()];
+    std::set<Expression>& currTemps = generatedTemporaries[DI->getBlock()];
+    std::set<Expression>& currAvail = availableOut[DI->getBlock()];     
+    
+    CalculateAvailOut(VN, maximalSet, *DI, currExps, currPhis,
+                      currTemps, currAvail, availableOut);
+  }
+  
+  PostDominatorTree &PDT = getAnalysis<PostDominatorTree>();
+  
+  // Second Phase of BuildSets - calculate ANTIC_IN
+  
+  bool changed = true;
+  unsigned iterations = 0;
+  while (changed) {
+    changed = false;
+    std::set<Expression> anticOut;
+    
+    // Top-down walk of the postdominator tree
+    for (df_iterator<PostDominatorTree::Node*> PDI = 
+         df_begin(PDT.getRootNode()), E = df_end(DT.getRootNode());
+         PDI != E; ++PDI) {
+      BasicBlock* BB = PDI->getBlock();
+      
+      std::set<Expression>& anticIn = anticipatedIn[BB];
+      std::set<Expression> old (anticIn.begin(), anticIn.end());
+      
+      if (BB->getTerminator()->getNumSuccessors() == 1) {
+         phi_translate(VN, anticIn, BB, anticOut);
+      } else if (BB->getTerminator()->getNumSuccessors() > 1) {
+        for (unsigned i = 0; i < BB->getTerminator()->getNumSuccessors(); ++i) {
+          BasicBlock* currSucc = BB->getTerminator()->getSuccessor(i);
+          std::set<Expression> temp;
+          if (i == 0)
+            temp.insert(maximalSet.begin(), maximalSet.end());
+          else
+            temp.insert(anticIn.begin(), anticIn.end());
+       
+          anticIn.clear();
+          std::insert_iterator<std::set<Expression> >  ai_ins(anticIn,
+                                                       anticIn.begin());
+                                                       
+          std::set_difference(anticipatedIn[currSucc].begin(),
+                              anticipatedIn[currSucc].end(),
+                              temp.begin(),
+                              temp.end(),
+                              ai_ins);
+        }
+      }
+      
+      std::set<Expression> S;
+      std::insert_iterator<std::set<Expression> >  s_ins(S, S.begin());
+      std::set_union(anticOut.begin(), anticOut.end(),
+                     generatedExpressions[BB].begin(),
+                     generatedExpressions[BB].end(),
+                     s_ins);
+      
+      anticIn.clear();
+      std::insert_iterator<std::set<Expression> >  antic_ins(anticIn, 
+                                                             anticIn.begin());
+      std::set_difference(S.begin(), S.end(),
+                          generatedTemporaries[BB].begin(),
+                          generatedTemporaries[BB].end(),
+                          antic_ins);
+      
+      clean(VN, anticIn);
+      
+      
+      
+      if (old != anticIn)
+        changed = true;
+      
+      anticOut.clear();
+    }
+    iterations++;
+  }
+  
+  /* printf("Iterations: %d\n", iterations);
+  
+  for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I) {
+    printf("Name: ");
+    printf(I->getName().c_str());
+    printf("\nTMP_GEN: ");
+    dump(VN, generatedTemporaries[I]);
+    printf("\nEXP_GEN: ");
+    dump(VN, generatedExpressions[I]);
+    //printf("\nANTIC_OUT: ");
+    //dump(VN, anticipatedOut[I]);
+    printf("\nANTIC_IN: \n");
+    dump(VN, anticipatedIn[I]);
+    printf("\n");
+  } */
+  
+  return false;
+}