diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index 834a95d7318..92270b5b647 100644
--- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -1993,6 +1993,12 @@ ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond,
           ValidScale(!CommonExprs->isZero(), Scale, UsersToProcess))
         continue;
 
+      // Avoid rewriting the compare instruction with an iv which has
+      // implicit extension or truncation built into it.
+      // TODO: This is over-conservative.
+      if (SE->getTypeSizeInBits(CondUse->getOffset()->getType()) != TyBits)
+        continue;
+
       // If scale is negative, use swapped predicate unless it's testing
       // for equality.
       if (Scale < 0 && !Cond->isEquality())
@@ -2005,16 +2011,11 @@ ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond,
         ConstantInt *CI = ConstantInt::get(NewCmpIntTy, NewCmpVal);
         NewCmpRHS = ConstantExpr::getIntToPtr(CI, NewCmpTy);
       }
-      NewOffset = CondUse->getOffset();
-      if (CondUse->isSigned())
-        NewOffset = SE->getNoopOrSignExtend(CondUse->getOffset(), NewCmpTy);
-      else
-        NewOffset = SE->getNoopOrZeroExtend(CondUse->getOffset(), NewCmpTy);
       NewOffset = TyBits == NewTyBits
-        ? SE->getMulExpr(NewOffset,
+        ? SE->getMulExpr(CondUse->getOffset(),
                          SE->getConstant(ConstantInt::get(CmpTy, Scale)))
         : SE->getConstant(ConstantInt::get(NewCmpIntTy,
-          cast<SCEVConstant>(NewOffset)->getValue()
+          cast<SCEVConstant>(CondUse->getOffset())->getValue()
             ->getSExtValue()*Scale));
       break;
     }
diff --git a/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-2.ll b/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-2.ll
index e3cb3a50953..f77aea39370 100644
--- a/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-2.ll
+++ b/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-2.ll
@@ -31,3 +31,28 @@ if.end52:		; preds = %for.cond.i.preheader
 	%indvar.next689 = add i64 %indvar688, 1		; <i64> [#uses=1]
 	br i1 %phitmp654, label %for.cond.i.preheader, label %if.end
 }
+
+define void @promote(%struct.dumperinfo* %di) nounwind {
+entry:
+	br label %if.end
+
+if.end:		; preds = %if.end52, %entry
+	br label %for.cond.i.preheader
+
+for.cond.i.preheader:		; preds = %if.end52, %if.end
+	%indvar688 = phi i32 [ 0, %if.end ], [ %indvar.next689, %if.end52 ]		; <i64> [#uses=3]
+	%tmp690 = shl i32 %indvar688, 12		; <i64> [#uses=1]
+	%pa.0642 = add i32 %tmp690, 0		; <i64> [#uses=1]
+	%tmp692693 = add i32 %indvar688, 1		; <i32> [#uses=1]
+	%phitmp = sext i32 %tmp692693 to i64		; <i64> [#uses=1]
+	br i1 false, label %if.end52, label %land.lhs.true.i
+
+land.lhs.true.i:		; preds = %for.cond.i.preheader
+	%shr2.i = lshr i32 %pa.0642, 18		; <i64> [#uses=0]
+	unreachable
+
+if.end52:		; preds = %for.cond.i.preheader
+	%phitmp654 = icmp ult i64 %phitmp, 512		; <i1> [#uses=1]
+	%indvar.next689 = add i32 %indvar688, 1		; <i64> [#uses=1]
+	br i1 %phitmp654, label %for.cond.i.preheader, label %if.end
+}