Index: llvm/include/llvm/Transforms/Vectorize/LoopVectorizationLegality.h
===================================================================
--- llvm/include/llvm/Transforms/Vectorize/LoopVectorizationLegality.h
+++ llvm/include/llvm/Transforms/Vectorize/LoopVectorizationLegality.h
@@ -313,6 +313,8 @@
   // Returns true if the NoNaN attribute is set on the function.
   bool hasFunNoNaNAttr() const { return HasFunNoNaNAttr; }
 
+  bool isLegalToInterleave();
+
 private:
   /// Return true if the pre-header, exiting and latch blocks of \p Lp and all
   /// its nested loops are considered legal for vectorization. These legal
Index: llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
===================================================================
--- llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
+++ llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
@@ -1263,4 +1263,18 @@
   return true;
 }
 
+bool LoopVectorizationLegality::isLegalToInterleave() {
+  // Check if reduction has invalid type for interleaving.
+  for (auto &Reduction : *getReductionVars()) {
+    auto Descriptor = Reduction.second;
+    auto ComputedType = Descriptor.getRecurrenceType();
+    auto IsSigned = Descriptor.isSigned();
+    // Eliminate degenerate types.
+    if (ComputedType->isIntegerTy(1) && IsSigned) {
+      return false;
+    }
+  }
+  return true;
+}
+
 } // namespace llvm
Index: llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
===================================================================
--- llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -8066,6 +8066,13 @@
     IC = CM.selectInterleaveCount(VF.Width, VF.Cost, LVI);
   }
 
+  // Check if it is legal to interleave the loop.
+  if (IC > 1 && !LVL.isLegalToInterleave()) {
+    LLVM_DEBUG(dbgs() << "LV: Not vectorizing: Can't interleave reduction.\n");
+    Hints.emitRemarkWithHints();
+    return false;
+  }
+
   // Identify the diagnostic messages that should be produced.
   std::pair<StringRef, std::string> VecDiagMsg, IntDiagMsg;
   bool VectorizeLoop = true, InterleaveLoop = true;