diff --git a/llvm/lib/Transforms/Coroutines/CoroSplit.cpp b/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
index 358f72d63fb82..39e909bf3316c 100644
--- a/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
+++ b/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
@@ -576,7 +576,7 @@ void CoroCloner::replaceRetconOrAsyncSuspendUses() {
   if (NewS->use_empty()) return;
 
   // Otherwise, we need to create an aggregate.
-  Value *Agg = UndefValue::get(NewS->getType());
+  Value *Agg = PoisonValue::get(NewS->getType());
   for (size_t I = 0, E = Args.size(); I != E; ++I)
     Agg = Builder.CreateInsertValue(Agg, Args[I], I);
 
@@ -897,7 +897,7 @@ void CoroCloner::create() {
   // frame.
   SmallVector<Instruction *> DummyArgs;
   for (Argument &A : OrigF.args()) {
-    DummyArgs.push_back(new FreezeInst(UndefValue::get(A.getType())));
+    DummyArgs.push_back(new FreezeInst(PoisonValue::get(A.getType())));
     VMap[&A] = DummyArgs.back();
   }
 
@@ -1055,7 +1055,7 @@ void CoroCloner::create() {
   // All uses of the arguments should have been resolved by this point,
   // so we can safely remove the dummy values.
   for (Instruction *DummyArg : DummyArgs) {
-    DummyArg->replaceAllUsesWith(UndefValue::get(DummyArg->getType()));
+    DummyArg->replaceAllUsesWith(PoisonValue::get(DummyArg->getType()));
     DummyArg->deleteValue();
   }
 
@@ -1901,7 +1901,7 @@ static void splitRetconCoroutine(Function &F, coro::Shape &Shape,
       if (ReturnPHIs.size() == 1) {
         RetV = CastedContinuation;
       } else {
-        RetV = UndefValue::get(RetTy);
+        RetV = PoisonValue::get(RetTy);
         RetV = Builder.CreateInsertValue(RetV, CastedContinuation, 0);
         for (size_t I = 1, E = ReturnPHIs.size(); I != E; ++I)
           RetV = Builder.CreateInsertValue(RetV, ReturnPHIs[I], I);
diff --git a/llvm/test/Transforms/Coroutines/coro-debug-dbg.values-not_used_in_frame.ll b/llvm/test/Transforms/Coroutines/coro-debug-dbg.values-not_used_in_frame.ll
index d90e255d290ad..ed76c67860ee1 100644
--- a/llvm/test/Transforms/Coroutines/coro-debug-dbg.values-not_used_in_frame.ll
+++ b/llvm/test/Transforms/Coroutines/coro-debug-dbg.values-not_used_in_frame.ll
@@ -4,8 +4,8 @@
 ; This file is based on coro-debug-frame-variable.ll.
 ; CHECK:  define internal fastcc void @f.resume(ptr noundef nonnull align 16 dereferenceable(80) %begin) !dbg ![[RESUME_FN_DBG_NUM:[0-9]+]]
 ; CHECK:       await.ready:
-; CHECK:         call void @llvm.dbg.value(metadata i32 undef, metadata ![[IVAR_RESUME:[0-9]+]], metadata !DIExpression(
-; CHECK:         call void @llvm.dbg.value(metadata i32 undef, metadata ![[JVAR_RESUME:[0-9]+]], metadata !DIExpression(
+; CHECK:         call void @llvm.dbg.value(metadata i32 poison, metadata ![[IVAR_RESUME:[0-9]+]], metadata !DIExpression(
+; CHECK:         call void @llvm.dbg.value(metadata i32 poison, metadata ![[JVAR_RESUME:[0-9]+]], metadata !DIExpression(
 ;
 ; CHECK: ![[RESUME_FN_DBG_NUM]] = distinct !DISubprogram(name: "foo", linkageName: "_Z3foov"
 ; CHECK: ![[IVAR_RESUME]] = !DILocalVariable(name: "i"
diff --git a/llvm/test/Transforms/Coroutines/coro-retcon-alloca-opaque-ptr.ll b/llvm/test/Transforms/Coroutines/coro-retcon-alloca-opaque-ptr.ll
index f07c88c63793a..879e368489a6a 100644
--- a/llvm/test/Transforms/Coroutines/coro-retcon-alloca-opaque-ptr.ll
+++ b/llvm/test/Transforms/Coroutines/coro-retcon-alloca-opaque-ptr.ll
@@ -12,7 +12,7 @@ define {ptr, ptr, i32} @f(ptr %buffer, i32 %n, { i32 } %dummy) {
 ; CHECK-NEXT:    store i32 [[N:%.*]], ptr [[N_VAL_SPILL_ADDR]], align 4
 ; CHECK-NEXT:    [[TMP0:%.*]] = tail call ptr @allocate(i32 [[N]])
 ; CHECK-NEXT:    store ptr [[TMP0]], ptr [[BUFFER]], align 8
-; CHECK-NEXT:    [[TMP1:%.*]] = insertvalue { ptr, ptr, i32 } { ptr @f.resume.0, ptr undef, i32 undef }, ptr [[TMP0]], 1
+; CHECK-NEXT:    [[TMP1:%.*]] = insertvalue { ptr, ptr, i32 } { ptr @f.resume.0, ptr poison, i32 poison }, ptr [[TMP0]], 1
 ; CHECK-NEXT:    [[TMP2:%.*]] = insertvalue { ptr, ptr, i32 } [[TMP1]], i32 [[N]], 2
 ; CHECK-NEXT:    ret { ptr, ptr, i32 } [[TMP2]]
 ;
@@ -47,7 +47,7 @@ define {ptr, i32} @g(ptr %buffer, i32 %n) {
 ; CHECK-NEXT:    [[TMP0:%.*]] = zext i32 [[N]] to i64
 ; CHECK-NEXT:    [[TMP1:%.*]] = alloca i8, i64 [[TMP0]], align 8
 ; CHECK-NEXT:    tail call void @use(ptr nonnull [[TMP1]])
-; CHECK-NEXT:    [[TMP2:%.*]] = insertvalue { ptr, i32 } { ptr @g.resume.0, i32 undef }, i32 [[N]], 1
+; CHECK-NEXT:    [[TMP2:%.*]] = insertvalue { ptr, i32 } { ptr @g.resume.0, i32 poison }, i32 [[N]], 1
 ; CHECK-NEXT:    ret { ptr, i32 } [[TMP2]]
 ;
 entry:
diff --git a/llvm/test/Transforms/Coroutines/coro-retcon-alloca.ll b/llvm/test/Transforms/Coroutines/coro-retcon-alloca.ll
index a4b6945b58798..ab3da8cde729a 100644
--- a/llvm/test/Transforms/Coroutines/coro-retcon-alloca.ll
+++ b/llvm/test/Transforms/Coroutines/coro-retcon-alloca.ll
@@ -11,7 +11,7 @@ define {ptr, ptr, i32} @f(ptr %buffer, i32 %n) {
 ; CHECK-NEXT:    store i32 [[N:%.*]], ptr [[N_VAL_SPILL_ADDR]], align 4
 ; CHECK-NEXT:    [[TMP0:%.*]] = tail call ptr @allocate(i32 [[N]])
 ; CHECK-NEXT:    store ptr [[TMP0]], ptr [[BUFFER]], align 8
-; CHECK-NEXT:    [[TMP1:%.*]] = insertvalue { ptr, ptr, i32 } { ptr @f.resume.0, ptr undef, i32 undef }, ptr [[TMP0]], 1
+; CHECK-NEXT:    [[TMP1:%.*]] = insertvalue { ptr, ptr, i32 } { ptr @f.resume.0, ptr poison, i32 poison }, ptr [[TMP0]], 1
 ; CHECK-NEXT:    [[TMP2:%.*]] = insertvalue { ptr, ptr, i32 } [[TMP1]], i32 [[N]], 2
 ; CHECK-NEXT:    ret { ptr, ptr, i32 } [[TMP2]]
 ;
@@ -47,7 +47,7 @@ define {ptr, i32} @g(ptr %buffer, i32 %n) {
 ; CHECK-NEXT:    [[TMP0:%.*]] = zext i32 [[N]] to i64
 ; CHECK-NEXT:    [[TMP1:%.*]] = alloca i8, i64 [[TMP0]], align 8
 ; CHECK-NEXT:    tail call void @use(ptr nonnull [[TMP1]])
-; CHECK-NEXT:    [[TMP2:%.*]] = insertvalue { ptr, i32 } { ptr @g.resume.0, i32 undef }, i32 [[N]], 1
+; CHECK-NEXT:    [[TMP2:%.*]] = insertvalue { ptr, i32 } { ptr @g.resume.0, i32 poison }, i32 [[N]], 1
 ; CHECK-NEXT:    ret { ptr, i32 } [[TMP2]]
 ;
 entry:
@@ -80,7 +80,7 @@ define {ptr, i32} @h(ptr %buffer, i32 %n) {
 ; CHECK-LABEL: @h(
 ; CHECK-NEXT:  coro.return:
 ; CHECK-NEXT:    store i32 [[N:%.*]], ptr [[BUFFER:%.*]], align 4
-; CHECK-NEXT:    [[TMP0:%.*]] = insertvalue { ptr, i32 } { ptr @h.resume.0, i32 undef }, i32 [[N]], 1
+; CHECK-NEXT:    [[TMP0:%.*]] = insertvalue { ptr, i32 } { ptr @h.resume.0, i32 poison }, i32 [[N]], 1
 ; CHECK-NEXT:    ret { ptr, i32 } [[TMP0]]
 ;
 entry:
@@ -113,7 +113,7 @@ define {ptr, i32} @i(ptr %buffer, i32 %n) {
 ; CHECK-LABEL: @i(
 ; CHECK-NEXT:  coro.return:
 ; CHECK-NEXT:    store i32 [[N:%.*]], ptr [[BUFFER:%.*]], align 4
-; CHECK-NEXT:    [[TMP0:%.*]] = insertvalue { ptr, i32 } { ptr @i.resume.0, i32 undef }, i32 [[N]], 1
+; CHECK-NEXT:    [[TMP0:%.*]] = insertvalue { ptr, i32 } { ptr @i.resume.0, i32 poison }, i32 [[N]], 1
 ; CHECK-NEXT:    ret { ptr, i32 } [[TMP0]]
 ;
 entry:
@@ -145,7 +145,7 @@ define {ptr, i32} @j(ptr %buffer, i32 %n) {
 ; CHECK-LABEL: @j(
 ; CHECK-NEXT:  coro.return:
 ; CHECK-NEXT:    store i32 [[N:%.*]], ptr [[BUFFER:%.*]], align 4
-; CHECK-NEXT:    [[TMP0:%.*]] = insertvalue { ptr, i32 } { ptr @j.resume.0, i32 undef }, i32 [[N]], 1
+; CHECK-NEXT:    [[TMP0:%.*]] = insertvalue { ptr, i32 } { ptr @j.resume.0, i32 poison }, i32 [[N]], 1
 ; CHECK-NEXT:    ret { ptr, i32 } [[TMP0]]
 ;
 entry:
@@ -181,7 +181,7 @@ define {ptr, i32} @k(ptr %buffer, i32 %n, i1 %cond) {
 ; CHECK-NEXT:    [[SIZE:%.*]] = tail call i32 @getSize()
 ; CHECK-NEXT:    br i1 [[COND:%.*]], label [[ALLOCA_BLOCK:%.*]], label [[CORO_RETURN:%.*]]
 ; CHECK:       coro.return:
-; CHECK-NEXT:    [[TMP0:%.*]] = insertvalue { ptr, i32 } { ptr @k.resume.0, i32 undef }, i32 [[N:%.*]], 1
+; CHECK-NEXT:    [[TMP0:%.*]] = insertvalue { ptr, i32 } { ptr @k.resume.0, i32 poison }, i32 [[N:%.*]], 1
 ; CHECK-NEXT:    ret { ptr, i32 } [[TMP0]]
 ; CHECK:       alloca_block:
 ; CHECK-NEXT:    [[TMP1:%.*]] = zext i32 [[SIZE]] to i64
diff --git a/llvm/test/Transforms/Coroutines/coro-retcon-once-value.ll b/llvm/test/Transforms/Coroutines/coro-retcon-once-value.ll
index eb4626dceaf29..c76a76c5fb85a 100644
--- a/llvm/test/Transforms/Coroutines/coro-retcon-once-value.ll
+++ b/llvm/test/Transforms/Coroutines/coro-retcon-once-value.ll
@@ -12,7 +12,7 @@ define {ptr, i32} @f(ptr %buffer, ptr %array) {
 ; CHECK-NEXT:    [[LOAD_POS:%.*]] = icmp sgt i32 [[LOAD]], 0
 ; CHECK-NEXT:    [[SPEC_SELECT:%.*]] = select i1 [[LOAD_POS]], ptr @f.resume.0, ptr @f.resume.1
 ; CHECK-NEXT:    [[SPEC_SELECT4:%.*]] = tail call i32 @llvm.smax.i32(i32 [[LOAD]], i32 0)
-; CHECK-NEXT:    [[TMP0:%.*]] = insertvalue { ptr, i32 } undef, ptr [[SPEC_SELECT]], 0
+; CHECK-NEXT:    [[TMP0:%.*]] = insertvalue { ptr, i32 } poison, ptr [[SPEC_SELECT]], 0
 ; CHECK-NEXT:    [[TMP1:%.*]] = insertvalue { ptr, i32 } [[TMP0]], i32 [[SPEC_SELECT4]], 1
 ; CHECK-NEXT:    ret { ptr, i32 } [[TMP1]]
 ;
diff --git a/llvm/test/Transforms/Coroutines/coro-retcon-once-value2.ll b/llvm/test/Transforms/Coroutines/coro-retcon-once-value2.ll
index 83c293f0a44f6..17a0a1d0e6b9e 100644
--- a/llvm/test/Transforms/Coroutines/coro-retcon-once-value2.ll
+++ b/llvm/test/Transforms/Coroutines/coro-retcon-once-value2.ll
@@ -44,7 +44,7 @@ declare void @print(i32)
 ; CHECK-NEXT:    store ptr [[PTR:%.*]], ptr [[TMP0]], align 8
 ; CHECK-NEXT:    [[OLDVALUE:%.*]] = load i32, ptr [[PTR]], align 4
 ; CHECK-NEXT:    store i32 [[OLDVALUE]], ptr [[TEMP]], align 4
-; CHECK-NEXT:    [[TMP2:%.*]] = insertvalue { ptr, ptr } { ptr @f.resume.0, ptr undef }, ptr [[TEMP]], 1
+; CHECK-NEXT:    [[TMP2:%.*]] = insertvalue { ptr, ptr } { ptr @f.resume.0, ptr poison }, ptr [[TEMP]], 1
 ; CHECK-NEXT:    ret { ptr, ptr } [[TMP2]]
 ;
 ;
diff --git a/llvm/test/Transforms/Coroutines/coro-retcon-opaque-ptr.ll b/llvm/test/Transforms/Coroutines/coro-retcon-opaque-ptr.ll
index 38629efef6d22..868a9c4966756 100644
--- a/llvm/test/Transforms/Coroutines/coro-retcon-opaque-ptr.ll
+++ b/llvm/test/Transforms/Coroutines/coro-retcon-opaque-ptr.ll
@@ -54,7 +54,7 @@ define hidden { ptr, ptr } @g(ptr %buffer, ptr %ptr) {
 ; CHECK-NEXT:    [[TMP0:%.*]] = tail call ptr @allocate(i32 8)
 ; CHECK-NEXT:    store ptr [[TMP0]], ptr [[BUFFER:%.*]], align 8
 ; CHECK-NEXT:    store ptr [[PTR:%.*]], ptr [[TMP0]], align 8
-; CHECK-NEXT:    [[TMP1:%.*]] = insertvalue { ptr, ptr } { ptr @g.resume.0, ptr undef }, ptr [[PTR]], 1
+; CHECK-NEXT:    [[TMP1:%.*]] = insertvalue { ptr, ptr } { ptr @g.resume.0, ptr poison }, ptr [[PTR]], 1
 ; CHECK-NEXT:    ret { ptr, ptr } [[TMP1]]
 ;
 entry:
diff --git a/llvm/test/Transforms/Coroutines/coro-retcon-value.ll b/llvm/test/Transforms/Coroutines/coro-retcon-value.ll
index 27344ffe63c94..0b0f5dfd56c95 100644
--- a/llvm/test/Transforms/Coroutines/coro-retcon-value.ll
+++ b/llvm/test/Transforms/Coroutines/coro-retcon-value.ll
@@ -6,7 +6,7 @@ define {ptr, i32} @f(ptr %buffer, i32 %n) {
 ; CHECK-LABEL: @f(
 ; CHECK-NEXT:  coro.return:
 ; CHECK-NEXT:    store i32 [[N:%.*]], ptr [[BUFFER:%.*]], align 4
-; CHECK-NEXT:    [[TMP0:%.*]] = insertvalue { ptr, i32 } { ptr @f.resume.0, i32 undef }, i32 [[N]], 1
+; CHECK-NEXT:    [[TMP0:%.*]] = insertvalue { ptr, i32 } { ptr @f.resume.0, i32 poison }, i32 [[N]], 1
 ; CHECK-NEXT:    ret { ptr, i32 } [[TMP0]]
 ;
 entry:
diff --git a/llvm/test/Transforms/Coroutines/coro-retcon.ll b/llvm/test/Transforms/Coroutines/coro-retcon.ll
index b42f1c51855e6..774c609ed6c44 100644
--- a/llvm/test/Transforms/Coroutines/coro-retcon.ll
+++ b/llvm/test/Transforms/Coroutines/coro-retcon.ll
@@ -75,7 +75,7 @@ define hidden { ptr, ptr } @g(ptr %buffer, ptr %ptr) {
 ; CHECK-NEXT:    [[TMP0:%.*]] = tail call ptr @allocate(i32 8)
 ; CHECK-NEXT:    store ptr [[TMP0]], ptr [[BUFFER:%.*]], align 8
 ; CHECK-NEXT:    store ptr [[PTR:%.*]], ptr [[TMP0]], align 8
-; CHECK-NEXT:    [[TMP1:%.*]] = insertvalue { ptr, ptr } { ptr @g.resume.0, ptr undef }, ptr [[PTR]], 1
+; CHECK-NEXT:    [[TMP1:%.*]] = insertvalue { ptr, ptr } { ptr @g.resume.0, ptr poison }, ptr [[PTR]], 1
 ; CHECK-NEXT:    ret { ptr, ptr } [[TMP1]]
 ;
 ; CORO-LABEL: @g(
@@ -86,7 +86,7 @@ define hidden { ptr, ptr } @g(ptr %buffer, ptr %ptr) {
 ; CORO-NEXT:    store ptr [[PTR:%.*]], ptr [[PTR_SPILL_ADDR]], align 8
 ; CORO-NEXT:    [[PTR_RELOAD_ADDR:%.*]] = getelementptr inbounds [[G_FRAME]], ptr [[TMP0]], i32 0, i32 0
 ; CORO-NEXT:    [[PTR_RELOAD:%.*]] = load ptr, ptr [[PTR_RELOAD_ADDR]], align 8
-; CORO-NEXT:    [[TMP1:%.*]] = insertvalue { ptr, ptr } undef, ptr @g.resume.0, 0
+; CORO-NEXT:    [[TMP1:%.*]] = insertvalue { ptr, ptr } poison, ptr @g.resume.0, 0
 ; CORO-NEXT:    [[TMP2:%.*]] = insertvalue { ptr, ptr } [[TMP1]], ptr [[PTR_RELOAD]], 1
 ; CORO-NEXT:    ret { ptr, ptr } [[TMP2]]
 ;