Index: llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -2134,15 +2134,11 @@
 
     if (!C) continue;
 
-    // Ignore negative constants, as the code below doesn't handle them
-    // correctly. TODO: Remove this restriction.
-    if (!C->getValue().isStrictlyPositive()) continue;
-
     /* Add new PHINode. */
     PHINode *NewPH = PHINode::Create(DestTy, 2, "IV.S.", PH);
 
     /* create new increment. '++d' in above example. */
-    Constant *CFP = ConstantFP::get(DestTy, C->getZExtValue());
+    Constant *CFP = ConstantFP::get(DestTy, C->getSExtValue());
     BinaryOperator *NewIncr =
       BinaryOperator::Create(Incr->getOpcode() == Instruction::Add ?
                                Instruction::FAdd : Instruction::FSub,