Index: lib/Transforms/Scalar/Scalarizer.cpp
===================================================================
--- lib/Transforms/Scalar/Scalarizer.cpp
+++ lib/Transforms/Scalar/Scalarizer.cpp
@@ -247,6 +247,7 @@
 }
 
 bool Scalarizer::runOnFunction(Function &F) {
+  assert(Gathered.empty() && Scattered.empty());
   for (Function::iterator BBI = F.begin(), BBE = F.end(); BBI != BBE; ++BBI) {
     BasicBlock *BB = BBI;
     for (BasicBlock::iterator II = BB->begin(), IE = BB->end(); II != IE;) {
@@ -636,7 +637,9 @@
 // Delete the instructions that we scalarized.  If a full vector result
 // is still needed, recreate it using InsertElements.
 bool Scalarizer::finish() {
-  if (Gathered.empty())
+  // The presence of data in Gathered or Scattered indicates changes
+  // made to the Function.
+  if (Gathered.empty() && Scattered.empty())
     return false;
   for (GatherList::iterator GMI = Gathered.begin(), GME = Gathered.end();
        GMI != GME; ++GMI) {
Index: test/Transforms/Scalarizer/store-bug.ll
===================================================================
--- /dev/null
+++ test/Transforms/Scalarizer/store-bug.ll
@@ -0,0 +1,17 @@
+; RUN: opt -scalarizer -scalarize-load-store < %s
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+
+; This input caused the scalarizer not to clear cached results
+; properly.
+;
+; Any regressions should trigger an assert in the scalarizer.
+
+define void @func(<4 x float> %val, <4 x float> *%ptr) {
+  store <4 x float> %val, <4 x float> *%ptr
+  ret void
+}
+
+define void @func.copy(<4 x float> %val, <4 x float> *%ptr) {
+  store <4 x float> %val, <4 x float> *%ptr
+  ret void
+}