diff --git a/llvm/include/llvm/IR/IntrinsicInst.h b/llvm/include/llvm/IR/IntrinsicInst.h
--- a/llvm/include/llvm/IR/IntrinsicInst.h
+++ b/llvm/include/llvm/IR/IntrinsicInst.h
@@ -274,7 +274,7 @@
     for (Value *OldValue : location_ops()) {
       if (!RemovedValues.insert(OldValue).second)
         continue;
-      Value *Undef = UndefValue::get(OldValue->getType());
+      Value *Undef = PoisonValue::get(OldValue->getType());
       replaceVariableLocationOp(OldValue, Undef);
     }
   }
diff --git a/llvm/test/DebugInfo/Generic/assignment-tracking/loop-deletion/dead-loop.ll b/llvm/test/DebugInfo/Generic/assignment-tracking/loop-deletion/dead-loop.ll
--- a/llvm/test/DebugInfo/Generic/assignment-tracking/loop-deletion/dead-loop.ll
+++ b/llvm/test/DebugInfo/Generic/assignment-tracking/loop-deletion/dead-loop.ll
@@ -18,7 +18,7 @@
 ;; mistake.
 
 ; CHECK: for.end:
-; CHECK-NEXT: call void @llvm.dbg.assign(metadata i32 undef,{{.+}}, metadata !DIExpression({{.+}}), metadata ![[ID:[0-9]+]], metadata ptr %Counter, metadata !DIExpression())
+; CHECK-NEXT: call void @llvm.dbg.assign(metadata i32 poison,{{.+}}, metadata !DIExpression({{.+}}), metadata ![[ID:[0-9]+]], metadata ptr %Counter, metadata !DIExpression())
 ; CHECK-NEXT: store i32 2, ptr %Counter, align 4,{{.*}}!DIAssignID ![[ID]]
 
 define dso_local void @_Z3funv() local_unnamed_addr #0 !dbg !7 {
diff --git a/llvm/test/DebugInfo/Generic/assignment-tracking/salvage-value.ll b/llvm/test/DebugInfo/Generic/assignment-tracking/salvage-value.ll
--- a/llvm/test/DebugInfo/Generic/assignment-tracking/salvage-value.ll
+++ b/llvm/test/DebugInfo/Generic/assignment-tracking/salvage-value.ll
@@ -16,7 +16,7 @@
  call void @llvm.dbg.assign(metadata i32 %add1, metadata !32, metadata !DIExpression(), metadata !31, metadata ptr %p, metadata !DIExpression()), !dbg !16
 ;; %add1 is not salvaged as it requires two values and DIArgList is
 ;; not (yet) supported for dbg.assigns.
-; CHECK-NEXT: call void @llvm.dbg.assign(metadata i32 undef,{{.+}}, metadata !DIExpression(),{{.+}}, metadata ptr %p, metadata !DIExpression())
+; CHECK-NEXT: call void @llvm.dbg.assign(metadata i32 poison,{{.+}}, metadata !DIExpression(),{{.+}}, metadata ptr %p, metadata !DIExpression())
 
   %arrayidx0 = getelementptr inbounds i32, ptr %p, i32 0
   call void @llvm.dbg.assign(metadata i32 %x, metadata !14, metadata !DIExpression(), metadata !17, metadata ptr %arrayidx0, metadata !DIExpression()), !dbg !16
diff --git a/llvm/test/DebugInfo/Generic/pr40628.ll b/llvm/test/DebugInfo/Generic/pr40628.ll
--- a/llvm/test/DebugInfo/Generic/pr40628.ll
+++ b/llvm/test/DebugInfo/Generic/pr40628.ll
@@ -11,7 +11,7 @@
 ; being assigned the 'undef' value.
 
 ; CHECK:      @foo
-; CHECK-NEXT: dbg.value(metadata i32 undef, metadata ![[DEADVAR:[0-9]+]],
+; CHECK-NEXT: dbg.value(metadata i32 poison, metadata ![[DEADVAR:[0-9]+]],
 ; CHECK-NEXT: load
 ; CHECK-NEXT: dbg.value(metadata i32 %{{[0-9]+}}, metadata ![[LIVEVAR:[0-9]+]],
 ; CHECK-NEXT: store
diff --git a/llvm/test/DebugInfo/X86/dead-store-elimination-marks-undef.ll b/llvm/test/DebugInfo/X86/dead-store-elimination-marks-undef.ll
--- a/llvm/test/DebugInfo/X86/dead-store-elimination-marks-undef.ll
+++ b/llvm/test/DebugInfo/X86/dead-store-elimination-marks-undef.ll
@@ -8,7 +8,7 @@
 define dso_local i32 @main() local_unnamed_addr !dbg !7 {
   %1 = alloca i32, align 4
   %2 = load i32, ptr @b, align 1, !dbg !13
-  ; CHECK: call void @llvm.dbg.value(metadata i32 undef
+  ; CHECK: call void @llvm.dbg.value(metadata i32 poison
   call void @llvm.dbg.value(metadata i32 %2, metadata !12, metadata !DIExpression()), !dbg !13
   store i32 %2, ptr %1, align 4, !dbg !13
   ret i32 0, !dbg !13
diff --git a/llvm/test/DebugInfo/X86/licm-undef-dbg-value.ll b/llvm/test/DebugInfo/X86/licm-undef-dbg-value.ll
--- a/llvm/test/DebugInfo/X86/licm-undef-dbg-value.ll
+++ b/llvm/test/DebugInfo/X86/licm-undef-dbg-value.ll
@@ -1,7 +1,7 @@
 ; RUN: opt -passes=licm %s -S | FileCheck %s
 
 ; CHECK: for.body:
-; CHECK-NEXT: llvm.dbg.value(metadata i8 undef
+; CHECK-NEXT: llvm.dbg.value(metadata i8 poison
 
 ; The load is loop invariant. Check that we leave an undef dbg.value behind
 ; when licm sinks the instruction.
diff --git a/llvm/test/DebugInfo/limit-arglist-size.ll b/llvm/test/DebugInfo/limit-arglist-size.ll
--- a/llvm/test/DebugInfo/limit-arglist-size.ll
+++ b/llvm/test/DebugInfo/limit-arglist-size.ll
@@ -4,7 +4,7 @@
 ; referenced by a dbg.value to 16. This test checks that we do not exceed this
 ; limit during salvaging.
 
-; CHECK: DIArgList(i32 undef
+; CHECK: DIArgList(i32 poison
 ; CHECK-NOT: DW_OP_LLVM_arg, 16
 
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
diff --git a/llvm/test/DebugInfo/salvage-limit-expr-size.ll b/llvm/test/DebugInfo/salvage-limit-expr-size.ll
--- a/llvm/test/DebugInfo/salvage-limit-expr-size.ll
+++ b/llvm/test/DebugInfo/salvage-limit-expr-size.ll
@@ -13,8 +13,8 @@
   call void @llvm.dbg.value(metadata i32 %add.1, metadata !12, metadata !DIExpression(DW_OP_constu, 1, DW_OP_plus, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_stack_value)), !dbg !13
   call void @llvm.dbg.value(metadata i32 %add.2, metadata !12, metadata !DIExpression(DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_stack_value)), !dbg !13
   ;; These expressions should be set undef, as they would salvage up to exactly 129 elements.
-  ; CHECK-NEXT: call void @llvm.dbg.value(metadata i32 undef, metadata ![[VAR_C]]
-  ; CHECK-NEXT: call void @llvm.dbg.value(metadata i32 undef, metadata ![[VAR_C]]
+  ; CHECK-NEXT: call void @llvm.dbg.value(metadata i32 poison, metadata ![[VAR_C]]
+  ; CHECK-NEXT: call void @llvm.dbg.value(metadata i32 poison, metadata ![[VAR_C]]
   call void @llvm.dbg.value(metadata i32 %add.1, metadata !12, metadata !DIExpression(DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_stack_value)), !dbg !13
   call void @llvm.dbg.value(metadata i32 %add.2, metadata !12, metadata !DIExpression(DW_OP_constu, 1, DW_OP_plus, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_plus_uconst, 1, DW_OP_stack_value)), !dbg !13
   %mul = mul nsw i32 %a, %b, !dbg !15
diff --git a/llvm/test/Transforms/BDCE/pr41925.ll b/llvm/test/Transforms/BDCE/pr41925.ll
--- a/llvm/test/Transforms/BDCE/pr41925.ll
+++ b/llvm/test/Transforms/BDCE/pr41925.ll
@@ -29,10 +29,10 @@
 for.cond2thread-pre-split.preheader:              ; preds = %entry
   br label %for.cond2thread-pre-split, !dbg !23
 for.cond2thread-pre-split:                        ; preds = %for.cond2thread-pre-split.preheader, %for.inc7
-;CHECK: call void @llvm.dbg.value(metadata i8 undef
+;CHECK: call void @llvm.dbg.value(metadata i8 poison
   %l_177.06 = phi i8 [ %l_177.1.lcssa, %for.inc7 ], [ 2, %for.cond2thread-pre-split.preheader ]
   call void @llvm.dbg.value(metadata i8 %l_177.06, metadata !17, metadata !DIExpression()), !dbg !18
-;CHECK: call void @llvm.dbg.value(metadata i8 undef
+;CHECK: call void @llvm.dbg.value(metadata i8 poison
   %.pr1 = load i8, ptr @a, align 1, !dbg !24
   call void @llvm.dbg.value(metadata i8 %l_177.06, metadata !17, metadata !DIExpression()), !dbg !18
   %cmp42 = icmp sgt i8 %.pr1, -1, !dbg !27
@@ -42,8 +42,8 @@
   br label %for.body6, !dbg !28
 
 for.body6:                                        ; preds = %for.body6.preheader, %for.body6
-;CHECK: call void @llvm.dbg.value(metadata i8 undef
-;CHECK: call void @llvm.dbg.value(metadata i8 undef
+;CHECK: call void @llvm.dbg.value(metadata i8 poison
+;CHECK: call void @llvm.dbg.value(metadata i8 poison
   %l_177.13 = phi i8 [ %inc, %for.body6 ], [ %l_177.06, %for.body6.preheader ]
   call void @llvm.dbg.value(metadata i8 %l_177.13, metadata !17, metadata !DIExpression()), !dbg !18
   call void @llvm.dbg.value(metadata i8 %l_177.13, metadata !17, metadata !DIExpression(DW_OP_plus_uconst, 1, DW_OP_stack_value)), !dbg !18
@@ -61,7 +61,7 @@
   br label %for.inc7, !dbg !35
 
 for.inc7:                                         ; preds = %for.inc7.loopexit, %for.cond2thread-pre-split
-;CHECK: call void @llvm.dbg.value(metadata i8 undef
+;CHECK: call void @llvm.dbg.value(metadata i8 poison
   %l_177.1.lcssa = phi i8 [ %l_177.06, %for.cond2thread-pre-split ], [ %inc.lcssa, %for.inc7.loopexit ], !dbg !18
   %1 = load i8, ptr @b, align 1, !dbg !35
   %inc8 = add i8 %1, 1, !dbg !35
diff --git a/llvm/test/Transforms/InstCombine/debuginfo-dce.ll b/llvm/test/Transforms/InstCombine/debuginfo-dce.ll
--- a/llvm/test/Transforms/InstCombine/debuginfo-dce.ll
+++ b/llvm/test/Transforms/InstCombine/debuginfo-dce.ll
@@ -34,7 +34,7 @@
   call void @llvm.dbg.value(metadata %struct.entry* %1, metadata !18, metadata !20), !dbg !19
 ; CHECK: define void @salvage_load
 ; CHECK-NEXT: entry:
-; CHECK-NEXT: call void @llvm.dbg.value(metadata %struct.entry* undef
+; CHECK-NEXT: call void @llvm.dbg.value(metadata %struct.entry* poison
   store %struct.entry* %1, %struct.entry** %im_not_dead, align 8
   ret void, !dbg !21
 }
diff --git a/llvm/test/Transforms/InstCombine/debuginfo-sink.ll b/llvm/test/Transforms/InstCombine/debuginfo-sink.ll
--- a/llvm/test/Transforms/InstCombine/debuginfo-sink.ll
+++ b/llvm/test/Transforms/InstCombine/debuginfo-sink.ll
@@ -33,7 +33,7 @@
 ; value range.
 
 ; CHECK-LABEL: define i32 @bar(
-; CHECK:       call void @llvm.dbg.value(metadata ptr undef,
+; CHECK:       call void @llvm.dbg.value(metadata ptr poison,
 ; CHECK-NEXT:  br label %sink2
 
 define i32 @bar(ptr %a, i32 %b) !dbg !70 {
diff --git a/llvm/test/Transforms/InstCombine/erase-dbg-values-at-dead-alloc-site.ll b/llvm/test/Transforms/InstCombine/erase-dbg-values-at-dead-alloc-site.ll
--- a/llvm/test/Transforms/InstCombine/erase-dbg-values-at-dead-alloc-site.ll
+++ b/llvm/test/Transforms/InstCombine/erase-dbg-values-at-dead-alloc-site.ll
@@ -12,7 +12,7 @@
 ;
 ; RUN-ONCE-LABEL: @t1(
 ; RUN-ONCE-NEXT: llvm.dbg.value(metadata i32 %0, metadata [[t1_arg0:![0-9]+]], metadata !DIExpression())
-; RUN-ONCE-NEXT: llvm.dbg.value(metadata ptr undef, metadata [[t1_fake_ptr:![0-9]+]], metadata !DIExpression())
+; RUN-ONCE-NEXT: llvm.dbg.value(metadata ptr poison, metadata [[t1_fake_ptr:![0-9]+]], metadata !DIExpression())
 ; RUN-ONCE-NEXT: ret void
 define void @t1(i32) !dbg !9 {
   %2 = alloca i32, align 4
diff --git a/llvm/test/Transforms/InstCombine/pr43893.ll b/llvm/test/Transforms/InstCombine/pr43893.ll
--- a/llvm/test/Transforms/InstCombine/pr43893.ll
+++ b/llvm/test/Transforms/InstCombine/pr43893.ll
@@ -9,9 +9,9 @@
   %0 = load i8, ptr @a, align 1, !dbg !17
   %dec = add i8 %0, -1, !dbg !17
   store i8 %dec, ptr @a, align 1, !dbg !17
-;CHECK: call void @llvm.dbg.value(metadata i32 undef
+;CHECK: call void @llvm.dbg.value(metadata i32 poison
 ;CHECK: call void @llvm.dbg.value(metadata i32 -8
-;CHECK: call void @llvm.dbg.value(metadata i32 undef
+;CHECK: call void @llvm.dbg.value(metadata i32 poison
   %conv = sext i8 %dec to i32, !dbg !17
   %udiv = udiv i32 %conv, 4, !dbg !17
   call void @llvm.dbg.value(metadata i32 %udiv, metadata !18, metadata !DIExpression()), !dbg !19
diff --git a/llvm/test/Transforms/InstCombine/stacksave-debuginfo.ll b/llvm/test/Transforms/InstCombine/stacksave-debuginfo.ll
--- a/llvm/test/Transforms/InstCombine/stacksave-debuginfo.ll
+++ b/llvm/test/Transforms/InstCombine/stacksave-debuginfo.ll
@@ -8,7 +8,7 @@
 
 define ptr @test1(i32 %P) !dbg !6 {
 ; CHECK-LABEL: @test1(
-; CHECK-NEXT:    call void @llvm.dbg.value(metadata ptr undef
+; CHECK-NEXT:    call void @llvm.dbg.value(metadata ptr poison
 ; CHECK-NEXT:    [[TMP1:%.*]] = zext i32 [[P:%.*]] to i64, !dbg !13
 ; CHECK-NEXT:    [[A:%.*]] = alloca i32, i64 [[TMP1]], align 4, !dbg !13
 ; CHECK-NEXT:    call void @llvm.dbg.value(metadata ptr [[A]]
diff --git a/llvm/test/Transforms/LoopDeletion/diundef.ll b/llvm/test/Transforms/LoopDeletion/diundef.ll
--- a/llvm/test/Transforms/LoopDeletion/diundef.ll
+++ b/llvm/test/Transforms/LoopDeletion/diundef.ll
@@ -18,7 +18,7 @@
   %exitcond = icmp ne i32 %inc, 3, !dbg !23
   br i1 %exitcond, label %for.cond, label %for.end, !dbg !24, !llvm.loop !25
 
-; CHECK: call void @llvm.dbg.value(metadata i32 undef, metadata !16, metadata !DIExpression()), !dbg !17
+; CHECK: call void @llvm.dbg.value(metadata i32 poison, metadata !16, metadata !DIExpression()), !dbg !17
 ; CHECK-NEXT: %call = tail call i32 {{.*}} @patatino()
 for.end:                                          ; preds = %for.cond
   %call = tail call i32 (...) @patatino() #3, !dbg !27
diff --git a/llvm/test/Transforms/LoopStrengthReduce/dbg-preserve-1.ll b/llvm/test/Transforms/LoopStrengthReduce/dbg-preserve-1.ll
--- a/llvm/test/Transforms/LoopStrengthReduce/dbg-preserve-1.ll
+++ b/llvm/test/Transforms/LoopStrengthReduce/dbg-preserve-1.ll
@@ -3,7 +3,7 @@
 ; Test that LSR avoids crashing on very large integer inputs. It should
 ; discard the variable location by creating an undef dbg.value.
 ;
-; CHECK: call void @llvm.dbg.value(metadata i128 undef,
+; CHECK: call void @llvm.dbg.value(metadata i128 poison,
 
 source_filename = "<stdin>"
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
diff --git a/llvm/test/Transforms/Reassociate/reassociate_dbgvalue_discard.ll b/llvm/test/Transforms/Reassociate/reassociate_dbgvalue_discard.ll
--- a/llvm/test/Transforms/Reassociate/reassociate_dbgvalue_discard.ll
+++ b/llvm/test/Transforms/Reassociate/reassociate_dbgvalue_discard.ll
@@ -11,8 +11,8 @@
 define dso_local i32 @test1(i32 %a, i32 %b, i32 %c, i32 %d) local_unnamed_addr #0 !dbg !7 {
 ; CHECK-LABEL: @test1(
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    call void @llvm.dbg.value(metadata i32 undef, metadata !16, metadata !DIExpression()), !dbg !20
-; CHECK-NEXT:    call void @llvm.dbg.value(metadata i32 undef, metadata !17, metadata !DIExpression()), !dbg !21
+; CHECK-NEXT:    call void @llvm.dbg.value(metadata i32 poison, metadata !16, metadata !DIExpression()), !dbg !20
+; CHECK-NEXT:    call void @llvm.dbg.value(metadata i32 poison, metadata !17, metadata !DIExpression()), !dbg !21
 ; CHECK-NEXT:    [[M1:%.*]] = mul i32 [[D:%.*]], [[C:%.*]], !dbg !22
 ; CHECK-NEXT:    [[M3:%.*]] = mul i32 [[M1]], [[A:%.*]], !dbg !23
 ; CHECK-NEXT:    call void @llvm.dbg.value(metadata i32 [[M3]], metadata !18, metadata !DIExpression()), !dbg !24
diff --git a/llvm/test/Transforms/Reassociate/undef_intrinsics_when_deleting_instructions.ll b/llvm/test/Transforms/Reassociate/undef_intrinsics_when_deleting_instructions.ll
--- a/llvm/test/Transforms/Reassociate/undef_intrinsics_when_deleting_instructions.ll
+++ b/llvm/test/Transforms/Reassociate/undef_intrinsics_when_deleting_instructions.ll
@@ -4,11 +4,11 @@
 ; that gets dropped and cannot be salvaged.
 
 ; CHECK-NOT: %add = fadd fast float %a, %b
-; CHECK: call void @llvm.dbg.value(metadata float undef, metadata [[VAR_X:![0-9]+]], metadata !DIExpression())
+; CHECK: call void @llvm.dbg.value(metadata float poison, metadata [[VAR_X:![0-9]+]], metadata !DIExpression())
 
 ; CHECK-LABEL: if.then:
 ; CHECK-NOT: %add1 = fadd fast float %add, %c
-; CHECK: call void @llvm.dbg.value(metadata float undef, metadata [[VAR_Y:![0-9]+]], metadata !DIExpression())
+; CHECK: call void @llvm.dbg.value(metadata float poison, metadata [[VAR_Y:![0-9]+]], metadata !DIExpression())
 ; CHECK-LABEL: !0 =
 ; CHECK-DAG: [[VAR_Y]] = !DILocalVariable(name: "y"
 ; CHECK-DAG: [[VAR_X]] = !DILocalVariable(name: "x"