Index: include/llvm/Transforms/Utils/Local.h
===================================================================
--- include/llvm/Transforms/Utils/Local.h
+++ include/llvm/Transforms/Utils/Local.h
@@ -258,6 +258,11 @@
 bool ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
                                      LoadInst *LI, DIBuilder &Builder);
 
+/// Inserts a llvm.dbg.value intrinsic after a phi of an alloca'd value
+/// that has an associated llvm.dbg.decl intrinsic.
+bool ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
+                                     PHINode *LI, DIBuilder &Builder);
+
 /// Lowers llvm.dbg.declare intrinsics into appropriate set of
 /// llvm.dbg.value intrinsics.
 bool LowerDbgDeclare(Function &F);
Index: lib/Transforms/Utils/Local.cpp
===================================================================
--- lib/Transforms/Utils/Local.cpp
+++ lib/Transforms/Utils/Local.cpp
@@ -1057,6 +1057,24 @@
   return false;
 }
 
+/// See if there is a dbg.value intrinsic for DIVar for the PHI node.
+static bool PhiHasDebugValue(DILocalVariable *DIVar, 
+                             DIExpression *DIExpr,
+                             PHINode *APN) {
+  // Since we can't guarantee that the original dbg.declare instrinsic
+  // is removed by LowerDbgDeclare(), we need to make sure that we are
+  // not inserting the same dbg.value intrinsic over and over.
+  return any_of(APN->getParent()->getInstList(), [&](Instruction &I) {
+    DbgValueInst *DVI = dyn_cast<DbgValueInst>(&I);
+    if (!DVI)
+      return false;
+    return DVI->getValue() == APN &&
+           DVI->getOffset() == 0 &&
+           DVI->getVariable() == DIVar &&
+           DVI->getExpression() == DIExpr;
+  });
+}
+
 /// Inserts a llvm.dbg.value intrinsic before a store to an alloca'd value
 /// that has an associated llvm.dbg.decl intrinsic.
 bool llvm::ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
@@ -1124,6 +1142,23 @@
   return true;
 }
 
+/// Inserts a llvm.dbg.value intrinsic after a phi 
+/// that has an associated llvm.dbg.decl intrinsic.
+bool llvm::ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
+                                           PHINode *APN, DIBuilder &Builder) {
+  auto *DIVar = DDI->getVariable();
+  auto *DIExpr = DDI->getExpression();
+  assert(DIVar && "Missing variable");
+
+  if (PhiHasDebugValue(DIVar, DIExpr, APN))
+    return true;
+
+  Instruction *DbgValue = Builder.insertDbgValueIntrinsic(
+      APN, 0, DIVar, DIExpr, DDI->getDebugLoc(), (Instruction *)nullptr);
+  DbgValue->insertBefore(&*APN->getParent()->getFirstInsertionPt());
+  return true;
+}
+
 /// Determine whether this alloca is either a VLA or an array.
 static bool isArray(AllocaInst *AI) {
   return AI->isArrayAllocation() ||
Index: lib/Transforms/Utils/PromoteMemoryToRegister.cpp
===================================================================
--- lib/Transforms/Utils/PromoteMemoryToRegister.cpp
+++ lib/Transforms/Utils/PromoteMemoryToRegister.cpp
@@ -907,6 +907,8 @@
 
         // The currently active variable for this block is now the PHI.
         IncomingVals[AllocaNo] = APN;
+        if (DbgDeclareInst *DDI = AllocaDbgDeclares[AllocaNo])
+          ConvertDebugDeclareToDebugValue(DDI, APN, DIB);
 
         // Get the next phi node.
         ++PNI;
Index: test/Transforms/Util/mem2reg-dbg.ll
===================================================================
--- test/Transforms/Util/mem2reg-dbg.ll
+++ test/Transforms/Util/mem2reg-dbg.ll
@@ -0,0 +1,76 @@
+; RUN: opt -mem2reg -S < %s | FileCheck %s
+
+; Test that a @llvm.dbg.value node is created to describe the value returned by a phi node when
+; lowering a @llvm.dbg.declare node
+
+; Created from the C code, compiled with -O0 -g:
+;
+; int func(int a)
+; {
+;         int c = 1;
+;         if (a < 0 ) {
+;                 c = 12;
+;         }
+;         return c;
+; }
+
+; Function Attrs: nounwind
+define i32 @func(i32 %a) #0 !dbg !8 {
+entry:
+  %a.addr = alloca i32, align 4
+  %c = alloca i32, align 4
+  store i32 %a, i32* %a.addr, align 4
+  call void @llvm.dbg.declare(metadata i32* %a.addr, metadata !12, metadata !13), !dbg !14
+  call void @llvm.dbg.declare(metadata i32* %c, metadata !15, metadata !13), !dbg !16
+  store i32 1, i32* %c, align 4, !dbg !16
+  %0 = load i32, i32* %a.addr, align 4, !dbg !17
+  %cmp = icmp slt i32 %0, 0, !dbg !19
+  br i1 %cmp, label %if.then, label %if.end, !dbg !20
+
+if.then:                                          ; preds = %entry
+  store i32 12, i32* %c, align 4, !dbg !21
+  br label %if.end, !dbg !23
+
+if.end:                                           ; preds = %if.then, %entry
+  %1 = load i32, i32* %c, align 4, !dbg !24
+; CHECK: %c.0 = phi i32 [ 12, %if.then ], [ 1, %entry ]
+; CHECK-NEXT: call void @llvm.dbg.value(metadata i32 %c.0, i64 0, metadata !15, metadata !13), !dbg !16
+  ret i32 %1, !dbg !25
+}
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
+
+attributes #1 = { nounwind readnone }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5, !6}
+!llvm.ident = !{!7}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
+!1 = !DIFile(filename: "a.c", directory: "/tmp")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{i32 1, !"min_enum_size", i32 4}
+!7 = !{!"clang"}
+!8 = distinct !DISubprogram(name: "func", scope: !1, file: !1, line: 1, type: !9, isLocal: false, isDefinition: true, scopeLine: 2, flags: DIFlagPrototyped, isOptimized: false, unit: !0, variables: !2)
+!9 = !DISubroutineType(types: !10)
+!10 = !{!11, !11}
+!11 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
+!12 = !DILocalVariable(name: "a", arg: 1, scope: !8, file: !1, line: 1, type: !11)
+!13 = !DIExpression()
+!14 = !DILocation(line: 1, column: 14, scope: !8)
+!15 = !DILocalVariable(name: "c", scope: !8, file: !1, line: 3, type: !11)
+!16 = !DILocation(line: 3, column: 6, scope: !8)
+!17 = !DILocation(line: 4, column: 6, scope: !18)
+!18 = distinct !DILexicalBlock(scope: !8, file: !1, line: 4, column: 6)
+!19 = !DILocation(line: 4, column: 8, scope: !18)
+!20 = !DILocation(line: 4, column: 6, scope: !8)
+!21 = !DILocation(line: 5, column: 5, scope: !22)
+!22 = distinct !DILexicalBlock(scope: !18, file: !1, line: 4, column: 14)
+!23 = !DILocation(line: 6, column: 2, scope: !22)
+!24 = !DILocation(line: 7, column: 9, scope: !8)
+!25 = !DILocation(line: 7, column: 2, scope: !8)
+