diff --git a/llvm/include/llvm/IR/PatternMatch.h b/llvm/include/llvm/IR/PatternMatch.h
index dd30072ce571..e1e7c7268b5d 100644
--- a/llvm/include/llvm/IR/PatternMatch.h
+++ b/llvm/include/llvm/IR/PatternMatch.h
@@ -215,6 +215,7 @@ template <typename Predicate> struct cst_pred_ty : public Predicate {
         // 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 @@ template <typename Predicate> struct cst_pred_ty : public Predicate {
           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 @@ template <typename Predicate> struct cstfp_pred_ty : public Predicate {
         // 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 @@ template <typename Predicate> struct cstfp_pred_ty : public Predicate {
           auto *CF = dyn_cast<ConstantFP>(Elt);
           if (!CF || !this->isValue(CF->getValueAPF()))
             return false;
+          HasNonUndefElements = true;
         }
-        return true;
+        return HasNonUndefElements;
       }
     }
     return false;
diff --git a/llvm/test/Transforms/InstSimplify/shr-scalar-vector-consistency.ll b/llvm/test/Transforms/InstSimplify/shr-scalar-vector-consistency.ll
index f1bba37ff991..90725a153a2f 100644
--- a/llvm/test/Transforms/InstSimplify/shr-scalar-vector-consistency.ll
+++ b/llvm/test/Transforms/InstSimplify/shr-scalar-vector-consistency.ll
@@ -16,7 +16,7 @@ define i32 @test_scalar(i32 %a, i1 %b) {
 
 define <2 x i32> @test_vector(<2 x i32> %a, <2 x i1> %b) {
 ; CHECK-LABEL: @test_vector(
-; CHECK-NEXT:    ret <2 x i32> zeroinitializer
+; CHECK-NEXT:    ret <2 x i32> undef
 ;
   %c = sext <2 x i1> %b to <2 x i32>
   %d = ashr <2 x i32> undef, %c
diff --git a/llvm/test/Transforms/Reassociate/fp-expr.ll b/llvm/test/Transforms/Reassociate/fp-expr.ll
index dcbf835ba544..e616c52f28e6 100644
--- a/llvm/test/Transforms/Reassociate/fp-expr.ll
+++ b/llvm/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
 ;
diff --git a/llvm/unittests/IR/PatternMatch.cpp b/llvm/unittests/IR/PatternMatch.cpp
index 6b5686d53c66..976e42d0dbba 100644
--- a/llvm/unittests/IR/PatternMatch.cpp
+++ b/llvm/unittests/IR/PatternMatch.cpp
@@ -534,6 +534,62 @@ TEST_F(PatternMatchTest, VectorOps) {
   EXPECT_TRUE(A == Val);
 }
 
+TEST_F(PatternMatchTest, VectorUndefInt) {
+  Type *ScalarTy = IRB.getInt8Ty();
+  Type *VectorTy = VectorType::get(ScalarTy, 4);
+  Constant *ScalarUndef = UndefValue::get(ScalarTy);
+  Constant *VectorUndef = UndefValue::get(VectorTy);
+  Constant *ScalarZero = Constant::getNullValue(ScalarTy);
+  Constant *VectorZero = Constant::getNullValue(VectorTy);
+
+  SmallVector<Constant *, 4> Elems;
+  Elems.push_back(ScalarUndef);
+  Elems.push_back(ScalarZero);
+  Elems.push_back(ScalarUndef);
+  Elems.push_back(ScalarZero);
+  Constant *VectorZeroUndef = ConstantVector::get(Elems);
+
+  EXPECT_TRUE(match(ScalarUndef, m_Undef()));
+  EXPECT_TRUE(match(VectorUndef, m_Undef()));
+  EXPECT_FALSE(match(ScalarZero, m_Undef()));
+  EXPECT_FALSE(match(VectorZero, m_Undef()));
+  EXPECT_FALSE(match(VectorZeroUndef, m_Undef()));
+
+  EXPECT_FALSE(match(ScalarUndef, m_Zero()));
+  EXPECT_FALSE(match(VectorUndef, m_Zero()));
+  EXPECT_TRUE(match(ScalarZero, m_Zero()));
+  EXPECT_TRUE(match(VectorZero, m_Zero()));
+  EXPECT_TRUE(match(VectorZeroUndef, m_Zero()));
+}
+
+TEST_F(PatternMatchTest, VectorUndefFloat) {
+  Type *ScalarTy = IRB.getFloatTy();
+  Type *VectorTy = VectorType::get(ScalarTy, 4);
+  Constant *ScalarUndef = UndefValue::get(ScalarTy);
+  Constant *VectorUndef = UndefValue::get(VectorTy);
+  Constant *ScalarZero = Constant::getNullValue(ScalarTy);
+  Constant *VectorZero = Constant::getNullValue(VectorTy);
+
+  SmallVector<Constant *, 4> Elems;
+  Elems.push_back(ScalarUndef);
+  Elems.push_back(ScalarZero);
+  Elems.push_back(ScalarUndef);
+  Elems.push_back(ScalarZero);
+  Constant *VectorZeroUndef = ConstantVector::get(Elems);
+
+  EXPECT_TRUE(match(ScalarUndef, m_Undef()));
+  EXPECT_TRUE(match(VectorUndef, m_Undef()));
+  EXPECT_FALSE(match(ScalarZero, m_Undef()));
+  EXPECT_FALSE(match(VectorZero, m_Undef()));
+  EXPECT_FALSE(match(VectorZeroUndef, m_Undef()));
+
+  EXPECT_FALSE(match(ScalarUndef, m_AnyZeroFP()));
+  EXPECT_FALSE(match(VectorUndef, m_AnyZeroFP()));
+  EXPECT_TRUE(match(ScalarZero, m_AnyZeroFP()));
+  EXPECT_TRUE(match(VectorZero, m_AnyZeroFP()));
+  EXPECT_TRUE(match(VectorZeroUndef, m_AnyZeroFP()));
+}
+
 template <typename T> struct MutableConstTest : PatternMatchTest { };
 
 typedef ::testing::Types<std::tuple<Value*, Instruction*>,