diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -4671,9 +4671,17 @@
   if (Cmp && TheLoop->contains(Cmp) && Cmp->hasOneUse())
     addToWorklistIfAllowed(Cmp);
 
+  auto PrevVF = VF.divideCoefficientBy(2);
   // Return true if all lanes perform the same memory operation, and we can
   // thus chose to execute only one.
   auto isUniformMemOpUse = [&](Instruction *I) {
+    // If the value was already known to not be uniform for the previous
+    // (smaller VF), it cannot be uniform for the larger VF.
+    if (PrevVF.isVector()) {
+      auto Iter = Uniforms.find(PrevVF);
+      if (Iter != Uniforms.end() && !Iter->second.contains(I))
+        return false;
+    }
     if (!Legal->isUniformMemOp(*I))
       return false;
     if (isa<LoadInst>(I))