diff --git a/llvm/unittests/Analysis/BranchProbabilityInfoTest.cpp b/llvm/unittests/Analysis/BranchProbabilityInfoTest.cpp
index 898dfef83a6e39..efce2de560adb3 100644
--- a/llvm/unittests/Analysis/BranchProbabilityInfoTest.cpp
+++ b/llvm/unittests/Analysis/BranchProbabilityInfoTest.cpp
@@ -50,7 +50,7 @@ TEST_F(BranchProbabilityInfoTest, StressUnreachableHeuristic) {
 
   // define void @f() {
   // entry:
-  //   switch i32 undef, label %exit, [
+  //   switch i32 poison, label %exit, [
   //      i32 0, label %preexit
   //      ...                   ;;< Add lots of cases to stress the heuristic.
   //   ]
@@ -69,8 +69,8 @@ TEST_F(BranchProbabilityInfoTest, StressUnreachableHeuristic) {
 
   unsigned NumCases = 4096;
   auto *I32 = IntegerType::get(C, 32);
-  auto *Undef = UndefValue::get(I32);
-  auto *Switch = SwitchInst::Create(Undef, ExitBB, NumCases, EntryBB);
+  auto *Poison= PoisonValue::get(I32);
+  auto *Switch = SwitchInst::Create(Poison, ExitBB, NumCases, EntryBB);
   for (unsigned I = 0; I < NumCases; ++I)
     Switch->addCase(ConstantInt::get(I32, I), PreExitBB);
 
diff --git a/llvm/unittests/Analysis/MemorySSATest.cpp b/llvm/unittests/Analysis/MemorySSATest.cpp
index 81784bb2360975..0ebbc881d26ab3 100644
--- a/llvm/unittests/Analysis/MemorySSATest.cpp
+++ b/llvm/unittests/Analysis/MemorySSATest.cpp
@@ -705,7 +705,7 @@ TEST_F(MemorySSATest, PartialWalkerCacheWithPhis) {
   BasicBlock *IfThen = BasicBlock::Create(C, "B", F);
   BasicBlock *IfEnd = BasicBlock::Create(C, "C", F);
 
-  B.CreateCondBr(UndefValue::get(Type::getInt1Ty(C)), IfThen, IfEnd);
+  B.CreateCondBr(PoisonValue::get(Type::getInt1Ty(C)), IfThen, IfEnd);
 
   B.SetInsertPoint(IfThen);
   Instruction *FirstStore = B.CreateStore(Zero, AllocA);
diff --git a/llvm/unittests/Analysis/ScalarEvolutionTest.cpp b/llvm/unittests/Analysis/ScalarEvolutionTest.cpp
index 3450302f36f617..9b209b9f180c99 100644
--- a/llvm/unittests/Analysis/ScalarEvolutionTest.cpp
+++ b/llvm/unittests/Analysis/ScalarEvolutionTest.cpp
@@ -133,7 +133,7 @@ TEST_F(ScalarEvolutionsTest, SimplifiedPHI) {
   BasicBlock *LoopBB = BasicBlock::Create(Context, "loop", F);
   BasicBlock *ExitBB = BasicBlock::Create(Context, "exit", F);
   BranchInst::Create(LoopBB, EntryBB);
-  BranchInst::Create(LoopBB, ExitBB, UndefValue::get(Type::getInt1Ty(Context)),
+  BranchInst::Create(LoopBB, ExitBB, PoisonValue::get(Type::getInt1Ty(Context)),
                      LoopBB);
   ReturnInst::Create(Context, nullptr, ExitBB);
   auto *Ty = Type::getInt32Ty(Context);
@@ -328,11 +328,11 @@ TEST_F(ScalarEvolutionsTest, CompareSCEVComplexity) {
   for (int i = 0; i < 8; i++) {
     PHINode *Phi = cast<PHINode>(&*II++);
     Phi->addIncoming(Acc[i], LoopBB);
-    Phi->addIncoming(UndefValue::get(Ty), EntryBB);
+    Phi->addIncoming(PoisonValue::get(Ty), EntryBB);
   }
 
   BasicBlock *ExitBB = BasicBlock::Create(Context, "bb2", F);
-  BranchInst::Create(LoopBB, ExitBB, UndefValue::get(Type::getInt1Ty(Context)),
+  BranchInst::Create(LoopBB, ExitBB, PoisonValue::get(Type::getInt1Ty(Context)),
                      LoopBB);
 
   Acc[0] = BinaryOperator::CreateAdd(Acc[0], Acc[1], "", ExitBB);
@@ -491,7 +491,7 @@ TEST_F(ScalarEvolutionsTest, SCEVNormalization) {
       "  %iv1 = phi i32 [ %iv1.inc, %loop ], [ -2147483648, %loop.ph ] "
       "  %iv0.inc = add i32 %iv0, 1 "
       "  %iv1.inc = add i32 %iv1, 3 "
-      "  br i1 undef, label %for.end.loopexit, label %loop "
+      "  br i1 poison, label %for.end.loopexit, label %loop "
       " "
       "for.end.loopexit: "
       "  ret void "
@@ -503,14 +503,14 @@ TEST_F(ScalarEvolutionsTest, SCEVNormalization) {
       "  br label %loop_0 "
       " "
       "loop_0: "
-      "  br i1 undef, label %loop_0, label %loop_1 "
+      "  br i1 poison, label %loop_0, label %loop_1 "
       " "
       "loop_1: "
-      "  br i1 undef, label %loop_2, label %loop_1 "
+      "  br i1 poison, label %loop_2, label %loop_1 "
       " "
       " "
       "loop_2: "
-      "  br i1 undef, label %end, label %loop_2 "
+      "  br i1 poison, label %end, label %loop_2 "
       " "
       "end: "
       "  ret void "
@@ -914,7 +914,7 @@ TEST_F(ScalarEvolutionsTest, SCEVAddRecFromPHIwithLargeConstants) {
      %1 = shl i64 %0, 32
      %2 = ashr exact i64 %1, 32
      %3 = add i64 %2, -9223372036854775808
-     br i1 undef, label %exit, label %loop
+     br i1 poison, label %exit, label %loop
     exit:
      ret void
    */
@@ -929,7 +929,7 @@ TEST_F(ScalarEvolutionsTest, SCEVAddRecFromPHIwithLargeConstants) {
       ConstantInt::get(Context, APInt(64, 0x8000000000000000U, true));
   auto *Int64_32 = ConstantInt::get(Context, APInt(64, 32));
   auto *Br = BranchInst::Create(
-      LoopBB, ExitBB, UndefValue::get(Type::getInt1Ty(Context)), LoopBB);
+      LoopBB, ExitBB, PoisonValue::get(Type::getInt1Ty(Context)), LoopBB);
   auto *Phi =
       PHINode::Create(Type::getInt64Ty(Context), 2, "", Br->getIterator());
   auto *Shl = BinaryOperator::CreateShl(Phi, Int64_32, "", Br->getIterator());
@@ -973,7 +973,7 @@ TEST_F(ScalarEvolutionsTest, SCEVAddRecFromPHIwithLargeConstantAccum) {
      %2 = shl i32 %1, 16
      %3 = ashr exact i32 %2, 16
      %4 = add i32 %3, -2147483648
-     br i1 undef, label %exit, label %loop
+     br i1 poison, label %exit, label %loop
     exit:
      ret void
    */
@@ -987,7 +987,7 @@ TEST_F(ScalarEvolutionsTest, SCEVAddRecFromPHIwithLargeConstantAccum) {
   auto *MinInt32 = ConstantInt::get(Context, APInt(32, 0x80000000U));
   auto *Int32_16 = ConstantInt::get(Context, APInt(32, 16));
   auto *Br = BranchInst::Create(
-      LoopBB, ExitBB, UndefValue::get(Type::getInt1Ty(Context)), LoopBB);
+      LoopBB, ExitBB, PoisonValue::get(Type::getInt1Ty(Context)), LoopBB);
   auto *Phi = PHINode::Create(Int32Ty, 2, "", Br->getIterator());
   auto *Shl = BinaryOperator::CreateShl(Phi, Int32_16, "", Br->getIterator());
   auto *AShr =
diff --git a/llvm/unittests/IR/BasicBlockTest.cpp b/llvm/unittests/IR/BasicBlockTest.cpp
index 88ac6611742ce9..36e849471d1ed8 100644
--- a/llvm/unittests/IR/BasicBlockTest.cpp
+++ b/llvm/unittests/IR/BasicBlockTest.cpp
@@ -67,8 +67,8 @@ TEST(BasicBlockTest, PhiRange) {
   // Finally, let's iterate them, which is the thing we're trying to test.
   // We'll use this to wire up the rest of the incoming values.
   for (auto &PN : BB->phis()) {
-    PN.addIncoming(UndefValue::get(Int32Ty), BB1.get());
-    PN.addIncoming(UndefValue::get(Int32Ty), BB2.get());
+    PN.addIncoming(PoisonValue::get(Int32Ty), BB1.get());
+    PN.addIncoming(PoisonValue::get(Int32Ty), BB2.get());
   }
 
   // Test that we can use const iterators and generally that the iterators
diff --git a/llvm/unittests/Transforms/Utils/ScalarEvolutionExpanderTest.cpp b/llvm/unittests/Transforms/Utils/ScalarEvolutionExpanderTest.cpp
index 13bd69624867e9..6aff8406790d3b 100644
--- a/llvm/unittests/Transforms/Utils/ScalarEvolutionExpanderTest.cpp
+++ b/llvm/unittests/Transforms/Utils/ScalarEvolutionExpanderTest.cpp
@@ -95,7 +95,7 @@ TEST_F(ScalarEvolutionExpanderTest, ExpandPtrTypeSCEV) {
 
   const DataLayout &DL = F->getDataLayout();
   BranchInst *Br = BranchInst::Create(
-      LoopBB, ExitBB, UndefValue::get(Type::getInt1Ty(Context)), LoopBB);
+      LoopBB, ExitBB, PoisonValue::get(Type::getInt1Ty(Context)), LoopBB);
   AllocaInst *Alloca = new AllocaInst(I32Ty, DL.getAllocaAddrSpace(), "alloca",
                                       Br->getIterator());
   ConstantInt *Ci32 = ConstantInt::get(Context, APInt(32, 1));
@@ -172,7 +172,7 @@ TEST_F(ScalarEvolutionExpanderTest, SCEVZeroExtendExprNonIntegral) {
   Builder.SetInsertPoint(L);
   PHINode *Phi = Builder.CreatePHI(T_int64, 2);
   Value *Add = Builder.CreateAdd(Phi, ConstantInt::get(T_int64, 1), "add");
-  Builder.CreateCondBr(UndefValue::get(T_int1), L, Post);
+  Builder.CreateCondBr(PoisonValue::get(T_int1), L, Post);
   Phi->addIncoming(ConstantInt::get(T_int64, 0), LPh);
   Phi->addIncoming(Add, L);