diff --git a/llvm/include/llvm/IR/PatternMatch.h b/llvm/include/llvm/IR/PatternMatch.h
--- a/llvm/include/llvm/IR/PatternMatch.h
+++ b/llvm/include/llvm/IR/PatternMatch.h
@@ -2513,6 +2513,12 @@
       auto *Cond = Select->getCondition();
       auto *TVal = Select->getTrueValue();
       auto *FVal = Select->getFalseValue();
+
+      // Don't match a scalar select of bool vectors.
+      // Transforms expect a single type for operands if this matches.
+      if (Cond->getType() != Select->getType())
+        return false;
+
       if (Opcode == Instruction::And) {
         auto *C = dyn_cast<Constant>(FVal);
         if (C && C->isNullValue())
diff --git a/llvm/unittests/IR/PatternMatch.cpp b/llvm/unittests/IR/PatternMatch.cpp
--- a/llvm/unittests/IR/PatternMatch.cpp
+++ b/llvm/unittests/IR/PatternMatch.cpp
@@ -1730,10 +1730,12 @@
   // select i1 Scalar, <3 x i1> <i1 1, i1 1, i1 1>, <3 x i1> Vector
   Value *MixedTypeOr = IRB.CreateSelect(Scalar, T, Vector);
 
+  // We allow matching a real vector logical select,
+  // but not a scalar select of vector bools.
   EXPECT_TRUE(match(VecAnd, m_LogicalAnd(m_Value(), m_Value())));
-  EXPECT_TRUE(match(MixedTypeAnd, m_LogicalAnd(m_Value(), m_Value())));
+  EXPECT_FALSE(match(MixedTypeAnd, m_LogicalAnd(m_Value(), m_Value())));
   EXPECT_TRUE(match(VecOr, m_LogicalOr(m_Value(), m_Value())));
-  EXPECT_TRUE(match(MixedTypeOr, m_LogicalOr(m_Value(), m_Value())));
+  EXPECT_FALSE(match(MixedTypeOr, m_LogicalOr(m_Value(), m_Value())));
 }
 
 TEST_F(PatternMatchTest, VScale) {