diff --git a/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp b/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp
--- a/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp
+++ b/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp
@@ -484,8 +484,12 @@
                                                    : Range.TheStores) dbgs()
                                               << *SI << '\n';
                dbgs() << "With: " << *AMemSet << '\n');
-    if (!Range.TheStores.empty())
-      AMemSet->setDebugLoc(Range.TheStores[0]->getDebugLoc());
+    if (!Range.TheStores.empty()) {
+      SmallVector<const DILocation *, 4> StoreLocs;
+      for (auto *StoreInst : Range.TheStores)
+        StoreLocs.push_back(StoreInst->getDebugLoc().get());
+      AMemSet->setDebugLoc(DebugLoc(DILocation::getMergedLocations(StoreLocs)));
+    }
 
     if (MSSAU) {
       assert(LastMemDef && MemInsertPoint &&
diff --git a/llvm/test/Transforms/MemCpyOpt/memset-merged-loc.ll b/llvm/test/Transforms/MemCpyOpt/memset-merged-loc.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Transforms/MemCpyOpt/memset-merged-loc.ll
@@ -0,0 +1,69 @@
+; RUN: opt -memcpyopt -S < %s | FileCheck %s
+;; In test3 function, this test case checks whether the generated new memset
+;; preserves the debug locations.
+;; In test4 function, this test case checks whether the generated new memset
+;; merges the debug locations.
+; CHECK: define void @test3
+; CHECK: call void @llvm.memset.p0i8.i64(i8* align 4 %1, i8 0, i64 19, i1 false), !dbg ![[LOC1:[0-9]+]]
+source_filename = "abc_debug.ll"
+; CHECK: define void @test4
+; CHECK: call void @llvm.memset.p0i8.i64(i8* align 4 %1, i8 0, i64 19, i1 false), !dbg ![[LOC2:[0-9]+]]
+; CHECK: ![[LOC1]] = !DILocation(line: 5, column: 1, scope
+; CHECK: ![[LOC2]] = !DILocation(line: 0, scope:
+
+target triple = "x86_64-unknown-linux-gnu"
+
+define void @test3(i32* %P) !dbg !6 {
+entry:
+  %arrayidx = getelementptr inbounds i32, i32* %P, i64 1, !dbg !8
+  %add.ptrone = getelementptr inbounds i32, i32* %P, i64 2, !dbg !9
+  %add.ptrtwo = getelementptr inbounds i32, i32* %P, i64 3, !dbg !10
+  %0 = bitcast i32* %add.ptrtwo to i8*, !dbg !11
+  store i32 0, i32* %arrayidx, align 4, !dbg !12
+  store i32 0, i32* %add.ptrone, align 4, !dbg !12
+  tail call void @llvm.memset.p0i8.i64(i8* %0, i8 0, i64 11, i1 false), !dbg !12
+  ret void, !dbg !15
+}
+
+define void @test4(i32* %P) !dbg !16 {
+entry:
+  %arrayidx = getelementptr inbounds i32, i32* %P, i64 1, !dbg !17
+  %add.ptrone = getelementptr inbounds i32, i32* %P, i64 2, !dbg !18
+  %add.ptrtwo = getelementptr inbounds i32, i32* %P, i64 3, !dbg !19
+  %0 = bitcast i32* %add.ptrtwo to i8*, !dbg !20
+  store i32 0, i32* %arrayidx, align 4, !dbg !21
+  store i32 0, i32* %add.ptrone, align 4, !dbg !22
+  tail call void @llvm.memset.p0i8.i64(i8* %0, i8 0, i64 11, i1 false), !dbg !23
+  ret void, !dbg !24
+}
+
+; Function Attrs: argmemonly nofree nosync nounwind willreturn writeonly
+declare void @llvm.memset.p0i8.i64(i8* nocapture writeonly, i8, i64, i1 immarg) 
+
+!llvm.module.flags = !{!0}
+!llvm.dbg.cu = !{!1}
+!llvm.debugify = !{!4, !5}
+
+!0 = !{i32 2, !"Debug Info Version", i32 3}
+!1 = distinct !DICompileUnit(language: DW_LANG_C, file: !2, producer: "debugify", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !3)
+!2 = !DIFile(filename: "<stdin>", directory: "/")
+!3 = !{}
+!4 = !{i32 16}
+!5 = !{i32 0}
+!6 = distinct !DISubprogram(name: "test3", linkageName: "test3", scope: null, file: !2, line: 1, type: !7, scopeLine: 1, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !1, retainedNodes: !3)
+!7 = !DISubroutineType(types: !3)
+!8 = !DILocation(line: 1, column: 1, scope: !6)
+!9 = !DILocation(line: 2, column: 1, scope: !6)
+!10 = !DILocation(line: 3, column: 1, scope: !6)
+!11 = !DILocation(line: 4, column: 1, scope: !6)
+!12 = !DILocation(line: 5, column: 1, scope: !6)
+!15 = !DILocation(line: 8, column: 1, scope: !6)
+!16 = distinct !DISubprogram(name: "test4", linkageName: "test4", scope: null, file: !2, line: 9, type: !7, scopeLine: 9, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !1, retainedNodes: !3)
+!17 = !DILocation(line: 9, column: 1, scope: !16)
+!18 = !DILocation(line: 10, column: 1, scope: !16)
+!19 = !DILocation(line: 11, column: 1, scope: !16)
+!20 = !DILocation(line: 12, column: 1, scope: !16)
+!21 = !DILocation(line: 13, column: 1, scope: !16)
+!22 = !DILocation(line: 14, column: 1, scope: !16)
+!23 = !DILocation(line: 15, column: 1, scope: !16)
+!24 = !DILocation(line: 16, column: 1, scope: !16)