Index: include/llvm/IR/PatternMatch.h
===================================================================
--- include/llvm/IR/PatternMatch.h
+++ include/llvm/IR/PatternMatch.h
@@ -215,6 +215,7 @@
         // Non-splat vector constant: check each element for a match.
         unsigned NumElts = V->getType()->getVectorNumElements();
         assert(NumElts != 0 && "Constant vector with no elements?");
+        bool HasNonUndefElements = false;
         for (unsigned i = 0; i != NumElts; ++i) {
           Constant *Elt = C->getAggregateElement(i);
           if (!Elt)
@@ -224,8 +225,9 @@
           auto *CI = dyn_cast<ConstantInt>(Elt);
           if (!CI || !this->isValue(CI->getValue()))
             return false;
+          HasNonUndefElements = true;
         }
-        return true;
+        return HasNonUndefElements;
       }
     }
     return false;
@@ -272,6 +274,7 @@
         // Non-splat vector constant: check each element for a match.
         unsigned NumElts = V->getType()->getVectorNumElements();
         assert(NumElts != 0 && "Constant vector with no elements?");
+        bool HasNonUndefElements = false;
         for (unsigned i = 0; i != NumElts; ++i) {
           Constant *Elt = C->getAggregateElement(i);
           if (!Elt)
@@ -281,8 +284,9 @@
           auto *CF = dyn_cast<ConstantFP>(Elt);
           if (!CF || !this->isValue(CF->getValueAPF()))
             return false;
+          HasNonUndefElements = true;
         }
-        return true;
+        return HasNonUndefElements;
       }
     }
     return false;
Index: test/Transforms/InstSimplify/shr-scalar-vector-consistency.ll
===================================================================
--- /dev/null
+++ test/Transforms/InstSimplify/shr-scalar-vector-consistency.ll
@@ -0,0 +1,24 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -instsimplify -S | FileCheck %s
+
+; This tests checks optimization consistency for scalar and vector code.
+; If m_Zero() is able to match a vector undef, but not a scalar undef,
+; the two cases will simplify differently.
+
+define i32 @test_scalar(i32 %a, i1 %b) {
+; CHECK-LABEL: @test_scalar(
+; CHECK-NEXT:    ret i32 undef
+;
+  %c = sext i1 %b to i32
+  %d = ashr i32 undef, %c
+  ret i32 %d
+}
+
+define <2 x i32> @test_vector(<2 x i32> %a, <2 x i1> %b) {
+; CHECK-LABEL: @test_vector(
+; CHECK-NEXT:    ret <2 x i32> undef
+;
+  %c = sext <2 x i1> %b to <2 x i32>
+  %d = ashr <2 x i32> undef, %c
+  ret <2 x i32> %d
+}
Index: test/Transforms/Reassociate/fp-expr.ll
===================================================================
--- test/Transforms/Reassociate/fp-expr.ll
+++ test/Transforms/Reassociate/fp-expr.ll
@@ -4,8 +4,8 @@
 define void @test1() {
 ; CHECK-LABEL: @test1(
 ; CHECK-NEXT:    [[T1:%.*]] = tail call <4 x float> @blam()
-; CHECK-NEXT:    [[T23:%.*]] = fsub fast <4 x float> undef, [[T1]]
-; CHECK-NEXT:    [[T24:%.*]] = fadd fast <4 x float> [[T23]], undef
+; CHECK-NEXT:    [[T1_NEG:%.*]] = fsub fast <4 x float> <float -0.000000e+00, float -0.000000e+00, float -0.000000e+00, float -0.000000e+00>, [[T1]]
+; CHECK-NEXT:    [[T24:%.*]] = fadd fast <4 x float> [[T1_NEG]], undef
 ; CHECK-NEXT:    tail call void @wombat(<4 x float> [[T24]])
 ; CHECK-NEXT:    ret void
 ;