diff --git a/lib/Target/README.txt b/lib/Target/README.txt
index 5c97b8984c1..abb8ee6f499 100644
--- a/lib/Target/README.txt
+++ b/lib/Target/README.txt
@@ -74,26 +74,7 @@ This has a number of uses:
 //===---------------------------------------------------------------------===//
 
 We should recognized various "overflow detection" idioms and translate them into
-llvm.uadd.with.overflow and similar intrinsics.  For example, we compile this:
-
-size_t add(size_t a,size_t b) {
- if (a+b<a)
-   exit(0);
- return a+b;
-}
-
-into:
-
-	addq	%rdi, %rbx
-	cmpq	%rdi, %rbx
-	jae	LBB0_2
-
-when it would be better to generate:
-
-	addq	%rdi, %rbx
-	jno	LBB0_2
-
-Apparently some version of GCC knows this.  Here is a multiply idiom:
+llvm.uadd.with.overflow and similar intrinsics.  Here is a multiply idiom:
 
 unsigned int mul(unsigned int a,unsigned int b) {
  if ((unsigned long long)a*b>0xffffffff)
diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 86a0ed2652d..6c6d26c81c7 100644
--- a/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -1648,7 +1648,7 @@ static Instruction *ProcessUGT_ADDCST_ADD(ICmpInst &I, Value *A, Value *B,
   
   // Put the new code above the original add, in case there are any uses of the
   // add between the add and the compare.
-  Builder->SetInsertPoint(OrigAdd->getParent(), BasicBlock::iterator(OrigAdd));
+  Builder->SetInsertPoint(OrigAdd);
   
   Value *TruncA = Builder->CreateTrunc(A, NewType, A->getName()+".trunc");
   Value *TruncB = Builder->CreateTrunc(B, NewType, B->getName()+".trunc");
@@ -1664,6 +1664,35 @@ static Instruction *ProcessUGT_ADDCST_ADD(ICmpInst &I, Value *A, Value *B,
   return ExtractValueInst::Create(Call, 1, "sadd.overflow");
 }
 
+static Instruction *ProcessUAddIdiom(Instruction &I, Value *OrigAddV,
+                                     InstCombiner &IC) {
+  // Don't bother doing this transformation for pointers, don't do it for
+  // vectors.
+  if (!isa<IntegerType>(OrigAddV->getType())) return 0;
+  
+  // If the add is a constant expr, then we don't bother transforming it.
+  Instruction *OrigAdd = dyn_cast<Instruction>(OrigAddV);
+  if (OrigAdd == 0) return 0;
+  
+  Value *LHS = OrigAdd->getOperand(0), *RHS = OrigAdd->getOperand(1);
+  
+  // Put the new code above the original add, in case there are any uses of the
+  // add between the add and the compare.
+  InstCombiner::BuilderTy *Builder = IC.Builder;
+  Builder->SetInsertPoint(OrigAdd);
+
+  Module *M = I.getParent()->getParent()->getParent();
+  const Type *Ty = LHS->getType();
+  Value *F = Intrinsic::getDeclaration(M, Intrinsic::uadd_with_overflow, &Ty,1);
+  CallInst *Call = Builder->CreateCall2(F, LHS, RHS, "uadd");
+  Value *Add = Builder->CreateExtractValue(Call, 0);
+
+  IC.ReplaceInstUsesWith(*OrigAdd, Add);
+
+  // The original icmp gets replaced with the overflow value.
+  return ExtractValueInst::Create(Call, 1, "uadd.overflow");
+}
+
 
 Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
   bool Changed = false;
@@ -1726,11 +1755,11 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
   }
 
   unsigned BitWidth = 0;
-  if (TD)
-    BitWidth = TD->getTypeSizeInBits(Ty->getScalarType());
-  else if (Ty->isIntOrIntVectorTy())
+  if (Ty->isIntOrIntVectorTy())
     BitWidth = Ty->getScalarSizeInBits();
-
+  else if (TD)  // Pointers require TD info to get their size.
+    BitWidth = TD->getTypeSizeInBits(Ty->getScalarType());
+  
   bool isSignBit = false;
 
   // See if we are doing a comparison with a constant.
@@ -2225,6 +2254,22 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
     if (match(Op0, m_Not(m_Value(A))) &&
         match(Op1, m_Not(m_Value(B))))
       return new ICmpInst(I.getPredicate(), B, A);
+
+    // (a+b) <u a  --> llvm.uadd.with.overflow.
+    // (a+b) <u b  --> llvm.uadd.with.overflow.
+    if (I.getPredicate() == ICmpInst::ICMP_ULT &&
+        match(Op0, m_Add(m_Value(A), m_Value(B))) && 
+        (Op1 == A || Op1 == B))
+      if (Instruction *R = ProcessUAddIdiom(I, Op0, *this))
+        return R;
+                                 
+    // a >u (a+b)  --> llvm.uadd.with.overflow.
+    // b >u (a+b)  --> llvm.uadd.with.overflow.
+    if (I.getPredicate() == ICmpInst::ICMP_UGT &&
+        match(Op1, m_Add(m_Value(A), m_Value(B))) &&
+        (Op0 == A || Op0 == B))
+      if (Instruction *R = ProcessUAddIdiom(I, Op1, *this))
+        return R;
   }
   
   if (I.isEquality()) {
diff --git a/test/Transforms/InstCombine/overflow.ll b/test/Transforms/InstCombine/overflow.ll
index 6a53d27749a..9123283988d 100644
--- a/test/Transforms/InstCombine/overflow.ll
+++ b/test/Transforms/InstCombine/overflow.ll
@@ -97,3 +97,37 @@ if.end:                                           ; preds = %entry
 ; CHECK: ret i8
 }
 
+; CHECK: @test5
+; CHECK: llvm.uadd.with.overflow
+; CHECK: ret i64
+define i64 @test5(i64 %a, i64 %b) nounwind ssp {
+entry:
+  %add = add i64 %b, %a
+  %cmp = icmp ult i64 %add, %a
+  %Q = select i1 %cmp, i64 %b, i64 42
+  ret i64 %Q
+}
+
+; CHECK: @test6
+; CHECK: llvm.uadd.with.overflow
+; CHECK: ret i64
+define i64 @test6(i64 %a, i64 %b) nounwind ssp {
+entry:
+  %add = add i64 %b, %a
+  %cmp = icmp ult i64 %add, %b
+  %Q = select i1 %cmp, i64 %b, i64 42
+  ret i64 %Q
+}
+
+; CHECK: @test7
+; CHECK: llvm.uadd.with.overflow
+; CHECK: ret i64
+define i64 @test7(i64 %a, i64 %b) nounwind ssp {
+entry:
+  %add = add i64 %b, %a
+  %cmp = icmp ugt i64 %b, %add
+  %Q = select i1 %cmp, i64 %b, i64 42
+  ret i64 %Q
+}
+
+