diff --git a/lib/IR/Value.cpp b/lib/IR/Value.cpp
index 70035080999..e0b72dca3ed 100644
--- a/lib/IR/Value.cpp
+++ b/lib/IR/Value.cpp
@@ -18,6 +18,7 @@
 #include "llvm/IR/Constant.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DataLayout.h"
+#include "llvm/IR/DebugInfo.h"
 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/DerivedUser.h"
 #include "llvm/IR/GetElementPtrTypeIterator.h"
@@ -531,6 +532,17 @@ void Value::replaceNonMetadataUsesWith(Value *New) {
   doRAUW(New, ReplaceMetadataUses::No);
 }
 
+/// Replace llvm.dbg.* uses of MetadataAsValue(ValueAsMetadata(V)) outside BB
+/// with New.
+static void replaceDbgUsesOutsideBlock(Value *V, Value *New, BasicBlock *BB) {
+  SmallVector<DbgVariableIntrinsic *> DbgUsers;
+  findDbgUsers(DbgUsers, V);
+  for (auto *DVI : DbgUsers) {
+    if (DVI->getParent() != BB)
+      DVI->replaceVariableLocationOp(V, New);
+  }
+}
+
 // Like replaceAllUsesWith except it does not handle constants or basic blocks.
 // This routine leaves uses within BB.
 void Value::replaceUsesOutsideBlock(Value *New, BasicBlock *BB) {
@@ -541,6 +553,7 @@ void Value::replaceUsesOutsideBlock(Value *New, BasicBlock *BB) {
          "replaceUses of value with new value of different type!");
   assert(BB && "Basic block that may contain a use of 'New' must be defined\n");
 
+  replaceDbgUsesOutsideBlock(this, New, BB);
   replaceUsesWithIf(New, [BB](Use &U) {
     auto *I = dyn_cast<Instruction>(U.getUser());
     // Don't replace if it's an instruction in the BB basic block.
diff --git a/test/DebugInfo/Generic/instcombine-replaced-select-with-operand.ll b/test/DebugInfo/Generic/instcombine-replaced-select-with-operand.ll
new file mode 100644
index 00000000000..8251d71ef64
--- /dev/null
+++ b/test/DebugInfo/Generic/instcombine-replaced-select-with-operand.ll
@@ -0,0 +1,127 @@
+; RUN: opt -instcombine -S %s | FileCheck %s
+
+;; Ensure that debug uses of a select are replaced when the select is replaced
+;; with one of its operands in InstCombine's replacedSelectWithOperand.
+
+;; Based on IR generated from this source, compiled with -O2 -g:
+;;
+;; extern void* glob;
+;; struct Thing {
+;;   void *ptr;
+;;   void *get() {return ptr;}
+;; };
+;; Thing *two(void *in) {
+;;   if ((long)in & 1)
+;;     return nullptr;
+;;   return static_cast<Thing *>(in);
+;; }
+;; void one() {
+;;   if (Thing *a = two(glob))
+;;     // Without the fix we lose 'this' (a) in the inlined call below.
+;;     glob = a->get();
+;; }
+
+;; Look at the instruction:
+;;     %retval.0.i = select i1 %tobool.not.i, %struct.Thing* %2, %struct.Thing* null
+;; Note that %2 is a bitcast of %0.
+;; InstCombine replaces the use of %retval.0.i in if.then with %0 because
+;; if.then is only branched to when retval.0.is not null. Ensure that debug use
+;; of %retval.0.i is also replaced with %0.
+
+; CHECK: if.then:
+; CHECK-NEXT: call void @llvm.dbg.value(metadata i8* %0, metadata ![[THIS:[0-9]+]], metadata !DIExpression())
+; CHECK: ![[THIS]] = !DILocalVariable(name: "this",
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+%struct.Thing = type { i8* }
+
+@glob = external dso_local local_unnamed_addr global i8*, align 8
+
+define dso_local void @_Z3onev() local_unnamed_addr !dbg !29 {
+entry:
+  %0 = load i8*, i8** @glob, align 8, !dbg !35
+  call void @llvm.dbg.value(metadata i8* %0, metadata !22, metadata !DIExpression()), !dbg !40
+  %1 = ptrtoint i8* %0 to i64, !dbg !42
+  %and.i = and i64 %1, 1, !dbg !43
+  %tobool.not.i = icmp eq i64 %and.i, 0, !dbg !42
+  %2 = bitcast i8* %0 to %struct.Thing*, !dbg !44
+  %retval.0.i = select i1 %tobool.not.i, %struct.Thing* %2, %struct.Thing* null, !dbg !44
+  call void @llvm.dbg.value(metadata %struct.Thing* %retval.0.i, metadata !33, metadata !DIExpression()), !dbg !45
+  %tobool.not = icmp eq %struct.Thing* %retval.0.i, null, !dbg !46
+  br i1 %tobool.not, label %if.end, label %if.then, !dbg !47
+
+if.then:                                          ; preds = %entry
+  call void @llvm.dbg.value(metadata %struct.Thing* %retval.0.i, metadata !48, metadata !DIExpression()), !dbg !51
+  %ptr.i = getelementptr inbounds %struct.Thing, %struct.Thing* %retval.0.i, i64 0, i32 0, !dbg !53
+  %3 = load i8*, i8** %ptr.i, align 8, !dbg !53
+  store i8* %3, i8** @glob, align 8, !dbg !56
+  br label %if.end, !dbg !57
+
+if.end:                                           ; preds = %if.then, %entry
+  ret void, !dbg !58
+}
+
+declare void @llvm.dbg.value(metadata, metadata, metadata)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!14, !15, !16}
+!llvm.ident = !{!17}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 13.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, retainedTypes: !3, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "test.cpp", directory: "/")
+!2 = !{}
+!3 = !{!4, !5}
+!4 = !DIBasicType(name: "long int", size: 64, encoding: DW_ATE_signed)
+!5 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !6, size: 64)
+!6 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "Thing", file: !1, line: 2, size: 64, flags: DIFlagTypePassByValue, elements: !7, identifier: "_ZTS5Thing")
+!7 = !{!8, !10}
+!8 = !DIDerivedType(tag: DW_TAG_member, name: "ptr", scope: !6, file: !1, line: 3, baseType: !9, size: 64)
+!9 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: null, size: 64)
+!10 = !DISubprogram(name: "get", linkageName: "_ZN5Thing3getEv", scope: !6, file: !1, line: 4, type: !11, scopeLine: 4, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized)
+!11 = !DISubroutineType(types: !12)
+!12 = !{!9, !13}
+!13 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !6, size: 64, flags: DIFlagArtificial | DIFlagObjectPointer)
+!14 = !{i32 7, !"Dwarf Version", i32 4}
+!15 = !{i32 2, !"Debug Info Version", i32 3}
+!16 = !{i32 1, !"wchar_size", i32 4}
+!17 = !{!"clang version 13.0.0"}
+!18 = distinct !DISubprogram(name: "two", linkageName: "_Z3twoPv", scope: !1, file: !1, line: 6, type: !19, scopeLine: 6, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !21)
+!19 = !DISubroutineType(types: !20)
+!20 = !{!5, !9}
+!21 = !{!22}
+!22 = !DILocalVariable(name: "in", arg: 1, scope: !18, file: !1, line: 6, type: !9)
+!23 = !DILocation(line: 0, scope: !18)
+!24 = !DILocation(line: 7, column: 7, scope: !25)
+!25 = distinct !DILexicalBlock(scope: !18, file: !1, line: 7, column: 7)
+!26 = !DILocation(line: 7, column: 16, scope: !25)
+!27 = !DILocation(line: 7, column: 7, scope: !18)
+!28 = !DILocation(line: 10, column: 1, scope: !18)
+!29 = distinct !DISubprogram(name: "one", linkageName: "_Z3onev", scope: !1, file: !1, line: 11, type: !30, scopeLine: 11, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !32)
+!30 = !DISubroutineType(types: !31)
+!31 = !{null}
+!32 = !{!33}
+!33 = !DILocalVariable(name: "a", scope: !34, file: !1, line: 12, type: !5)
+!34 = distinct !DILexicalBlock(scope: !29, file: !1, line: 12, column: 14)
+!35 = !DILocation(line: 12, column: 22, scope: !34)
+!40 = !DILocation(line: 0, scope: !18, inlinedAt: !41)
+!41 = distinct !DILocation(line: 12, column: 18, scope: !34)
+!42 = !DILocation(line: 7, column: 7, scope: !25, inlinedAt: !41)
+!43 = !DILocation(line: 7, column: 16, scope: !25, inlinedAt: !41)
+!44 = !DILocation(line: 7, column: 7, scope: !18, inlinedAt: !41)
+!45 = !DILocation(line: 0, scope: !34)
+!46 = !DILocation(line: 12, column: 14, scope: !34)
+!47 = !DILocation(line: 12, column: 14, scope: !29)
+!48 = !DILocalVariable(name: "this", arg: 1, scope: !49, type: !5, flags: DIFlagArtificial | DIFlagObjectPointer)
+!49 = distinct !DISubprogram(name: "get", linkageName: "_ZN5Thing3getEv", scope: !6, file: !1, line: 4, type: !11, scopeLine: 4, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, declaration: !10, retainedNodes: !50)
+!50 = !{!48}
+!51 = !DILocation(line: 0, scope: !49, inlinedAt: !52)
+!52 = distinct !DILocation(line: 14, column: 15, scope: !34)
+!53 = !DILocation(line: 4, column: 23, scope: !49, inlinedAt: !52)
+!56 = !DILocation(line: 14, column: 10, scope: !34)
+!57 = !DILocation(line: 14, column: 5, scope: !34)
+!58 = !DILocation(line: 15, column: 1, scope: !29)
+!59 = !DILocation(line: 0, scope: !49)
+!60 = !DILocation(line: 4, column: 23, scope: !49)
+!61 = !DILocation(line: 4, column: 16, scope: !49)
diff --git a/unittests/IR/ValueTest.cpp b/unittests/IR/ValueTest.cpp
index 0c42e4632e8..f94eec89ad6 100644
--- a/unittests/IR/ValueTest.cpp
+++ b/unittests/IR/ValueTest.cpp
@@ -9,6 +9,7 @@
 #include "llvm/IR/Value.h"
 #include "llvm/AsmParser/Parser.h"
 #include "llvm/IR/Function.h"
+#include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/ModuleSlotTracker.h"
@@ -247,4 +248,68 @@ TEST(ValueTest, getLocalSlotDeath) {
 }
 #endif
 
+TEST(ValueTest, replaceUsesOutsideBlock) {
+  // Check that Value::replaceUsesOutsideBlock(New, BB) replaces uses outside
+  // BB, including dbg.* uses of MetadataAsValue(ValueAsMetadata(this)).
+  const auto *IR = R"(
+    define i32 @f() !dbg !6 {
+    entry:
+      %a = add i32 0, 1, !dbg !15
+      %b = add i32 0, 2, !dbg !15
+      %c = add i32 %a, 2, !dbg !15
+      call void @llvm.dbg.value(metadata i32 %a, metadata !9, metadata !DIExpression()), !dbg !15
+      br label %exit, !dbg !15
+
+    exit:
+      call void @llvm.dbg.value(metadata i32 %a, metadata !11, metadata !DIExpression()), !dbg !16
+      ret i32 %a, !dbg !16
+    }
+
+    declare void @llvm.dbg.value(metadata, metadata, metadata)
+
+    !llvm.dbg.cu = !{!0}
+    !llvm.module.flags = !{!5}
+
+    !0 = distinct !DICompileUnit(language: DW_LANG_C, file: !1, producer: "debugify", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
+    !1 = !DIFile(filename: "test.ll", directory: "/")
+    !2 = !{}
+    !5 = !{i32 2, !"Debug Info Version", i32 3}
+    !6 = distinct !DISubprogram(name: "f", linkageName: "f", scope: null, file: !1, line: 1, type: !7, isLocal: false, isDefinition: true, scopeLine: 1, isOptimized: true, unit: !0, retainedNodes: !8)
+    !7 = !DISubroutineType(types: !2)
+    !8 = !{!9, !11}
+    !9 = !DILocalVariable(name: "1", scope: !6, file: !1, line: 1, type: !10)
+    !10 = !DIBasicType(name: "ty32", size: 32, encoding: DW_ATE_signed)
+    !11 = !DILocalVariable(name: "2", scope: !6, file: !1, line: 2, type: !12)
+    !12 = !DIBasicType(name: "ty64", size: 64, encoding: DW_ATE_signed)
+    !15 = !DILocation(line: 1, column: 1, scope: !6)
+    !16 = !DILocation(line: 5, column: 1, scope: !6)
+  )";
+  LLVMContext Ctx;
+  SMDiagnostic Err;
+  std::unique_ptr<Module> M = parseAssemblyString(IR, Err, Ctx);
+  if (!M)
+    Err.print("ValueTest", errs());
+
+  auto GetNext = [](auto *I) { return &*++I->getIterator(); };
+
+  Function *F = M->getFunction("f");
+  // Entry.
+  BasicBlock *Entry = &F->front();
+  Instruction *A = &Entry->front();
+  Instruction *B = GetNext(A);
+  Instruction *C = GetNext(B);
+  auto *EntryDbg = cast<DbgValueInst>(GetNext(C));
+  // Exit.
+  BasicBlock *Exit = GetNext(Entry);
+  auto *ExitDbg = cast<DbgValueInst>(&Exit->front());
+  Instruction *Ret = GetNext(ExitDbg);
+
+  A->replaceUsesOutsideBlock(B, Entry);
+  // These users are in Entry so shouldn't be changed.
+  ASSERT_TRUE(C->getOperand(0) == cast<Value>(A));
+  ASSERT_TRUE(EntryDbg->getValue(0) == cast<Value>(A));
+  // These users are outside Entry so should be changed.
+  ASSERT_TRUE(ExitDbg->getValue(0) == cast<Value>(B));
+  ASSERT_TRUE(Ret->getOperand(0) == cast<Value>(B));
+}
 } // end anonymous namespace