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
@@ -1542,7 +1542,7 @@
   // through scalar predication or masked load/store or masked gather/scatter.
   // Superset of instructions that return true for isScalarWithPredication.
   bool isPredicatedInst(Instruction *I) {
-    if (!blockNeedsPredication(I->getParent()))
+    if (!blockNeedsPredicationForAnyReason(I->getParent()))
       return false;
     // Loads and stores that need some form of masked operation are predicated
     // instructions.
@@ -1596,7 +1596,10 @@
   /// Returns true if all loop blocks should be masked to fold tail loop.
   bool foldTailByMasking() const { return FoldTailByMasking; }
 
-  bool blockNeedsPredication(BasicBlock *BB) const {
+  /// Returns true if the instructions in this block requires predication
+  /// for any reason, e.g. because tail folding now requires a predicate
+  /// or because the block in the original loop was predicated.
+  bool blockNeedsPredicationForAnyReason(BasicBlock *BB) const {
     return foldTailByMasking() || Legal->blockNeedsPredication(BB);
   }
 
@@ -5254,7 +5257,7 @@
 }
 
 bool LoopVectorizationCostModel::isScalarWithPredication(Instruction *I) const {
-  if (!blockNeedsPredication(I->getParent()))
+  if (!blockNeedsPredicationForAnyReason(I->getParent()))
     return false;
   switch(I->getOpcode()) {
   default:
@@ -5301,7 +5304,8 @@
   // (either a gap at the end of a load-access that may result in a speculative
   // load, or any gaps in a store-access).
   bool PredicatedAccessRequiresMasking =
-      blockNeedsPredication(I->getParent()) && Legal->isMaskRequired(I);
+      blockNeedsPredicationForAnyReason(I->getParent()) &&
+      Legal->isMaskRequired(I);
   bool LoadAccessWithGapsRequiresEpilogMasking =
       isa<LoadInst>(I) && Group->requiresScalarEpilogue() &&
       !isScalarEpilogueAllowed();
@@ -6845,7 +6849,7 @@
   // determine if it would be better to not if-convert the blocks they are in.
   // If so, we also record the instructions to scalarize.
   for (BasicBlock *BB : TheLoop->blocks()) {
-    if (!blockNeedsPredication(BB))
+    if (!blockNeedsPredicationForAnyReason(BB))
       continue;
     for (Instruction &I : *BB)
       if (isScalarWithPredication(&I)) {
@@ -8138,7 +8142,7 @@
     return None;
 
   // Invalidate interleave groups if all blocks of loop will be predicated.
-  if (CM.blockNeedsPredication(OrigLoop->getHeader()) &&
+  if (CM.blockNeedsPredicationForAnyReason(OrigLoop->getHeader()) &&
       !useMaskedInterleavedAccesses(*TTI)) {
     LLVM_DEBUG(
         dbgs()
@@ -8748,7 +8752,7 @@
   VPValue *BlockMask = nullptr;
 
   if (OrigLoop->getHeader() == BB) {
-    if (!CM.blockNeedsPredication(BB))
+    if (!CM.blockNeedsPredicationForAnyReason(BB))
       return BlockMaskCache[BB] = BlockMask; // Loop incoming mask is all-one.
 
     // Create the block in mask as the first non-phi instruction in the block.