Index: llvm/lib/Transforms/Scalar/MergedLoadStoreMotion.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/MergedLoadStoreMotion.cpp
+++ llvm/lib/Transforms/Scalar/MergedLoadStoreMotion.cpp
@@ -249,12 +249,14 @@
   // Intersect optional metadata.
   S0->andIRFlags(S1);
   S0->dropUnknownNonDebugMetadata();
+  S0->applyMergedLocation(S0->getDebugLoc(), S1->getDebugLoc());
 
   // Create the new store to be inserted at the join point.
   StoreInst *SNew = cast<StoreInst>(S0->clone());
   Instruction *ANew = A0->clone();
   SNew->insertBefore(&*InsertPt);
   ANew->insertBefore(SNew);
+  ANew->applyMergedLocation(A0->getDebugLoc(), A1->getDebugLoc());
 
   assert(S0->getParent() == A0->getParent());
   assert(S1->getParent() == A1->getParent());
Index: llvm/test/DebugInfo/Generic/mldst-motion-dbg.ll
===================================================================
--- /dev/null
+++ llvm/test/DebugInfo/Generic/mldst-motion-dbg.ll
@@ -0,0 +1,79 @@
+; RUN: opt -passes=mldst-motion -S %s -o - | FileCheck %s
+
+;; $ cat test.cpp -n
+;;      1	void fun(int *a, int cond) {
+;;      2	  if (cond)
+;;      3	    a[1] = 1;
+;;      4	  else
+;;      5	    a[1] = 2;
+;;      6	}
+;;
+;; mldst-motion will merge and sink the stores in if.then and if.else into
+;; if.end. The resultant PHI, gep and store should be attributed line zero
+;; with the innermost common scope rather than picking a debug location from
+;; one of the original stores.
+
+; CHECK: if.end:
+; CHECK-NEXT: %.sink = phi i32 [ 2, %if.else ], [ 1, %if.then ], !dbg ![[dbg:[0-9]+]]
+; CHECK-NEXT: %0 = getelementptr inbounds i32, i32* %a, i64 1, !dbg ![[dbg:[0-9]+]]
+; CHECK-NEXT: store i32 %.sink, i32* %0, align 4, !dbg ![[dbg:[0-9]+]]
+
+; CHECK-DAG: ![[dbg]] = !DILocation(line: 0, scope: ![[scp:[0-9]+]]
+; CHECK-DAG: ![[scp]] = distinct !DILexicalBlock(scope: ![[fun:[0-9]+]]
+; CHECK-DAG: ![[fun]] = distinct !DISubprogram(name: "fun",
+
+define dso_local void @_Z3funPii(i32* nocapture noundef writeonly %a, i32 noundef %cond) local_unnamed_addr #0 !dbg !7 {
+entry:
+  call void @llvm.dbg.value(metadata i32* %a, metadata !13, metadata !DIExpression()), !dbg !15
+  call void @llvm.dbg.value(metadata i32 %cond, metadata !14, metadata !DIExpression()), !dbg !15
+  %tobool.not = icmp eq i32 %cond, 0, !dbg !16
+  br i1 %tobool.not, label %if.else, label %if.then, !dbg !18
+
+if.then:                                          ; preds = %entry
+  %arrayidx = getelementptr inbounds i32, i32* %a, i64 1, !dbg !19
+  store i32 1, i32* %arrayidx, align 4, !dbg !20, !tbaa !21
+  br label %if.end, !dbg !19
+
+if.else:                                          ; preds = %entry
+  %arrayidx1 = getelementptr inbounds i32, i32* %a, i64 1, !dbg !25
+  store i32 2, i32* %arrayidx1, align 4, !dbg !26, !tbaa !21
+  br label %if.end
+
+if.end:                                           ; preds = %if.else, %if.then
+  ret void, !dbg !27
+}
+
+declare void @llvm.dbg.value(metadata, metadata, metadata)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!2, !3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 14.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "test.cpp", directory: "/")
+!2 = !{i32 7, !"Dwarf Version", i32 5}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!4 = !{i32 1, !"wchar_size", i32 4}
+!5 = !{i32 7, !"uwtable", i32 1}
+!6 = !{!"clang version 14.0.0"}
+!7 = distinct !DISubprogram(name: "fun", linkageName: "_Z3funPii", scope: !1, file: !1, line: 1, type: !8, scopeLine: 1, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !12)
+!8 = !DISubroutineType(types: !9)
+!9 = !{null, !10, !11}
+!10 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !11, size: 64)
+!11 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!12 = !{!13, !14}
+!13 = !DILocalVariable(name: "a", arg: 1, scope: !7, file: !1, line: 1, type: !10)
+!14 = !DILocalVariable(name: "cond", arg: 2, scope: !7, file: !1, line: 1, type: !11)
+!15 = !DILocation(line: 0, scope: !7)
+!16 = !DILocation(line: 2, column: 7, scope: !17)
+!17 = distinct !DILexicalBlock(scope: !7, file: !1, line: 2, column: 7)
+!18 = !DILocation(line: 2, column: 7, scope: !7)
+!19 = !DILocation(line: 3, column: 5, scope: !17)
+!20 = !DILocation(line: 3, column: 10, scope: !17)
+!21 = !{!22, !22, i64 0}
+!22 = !{!"int", !23, i64 0}
+!23 = !{!"omnipotent char", !24, i64 0}
+!24 = !{!"Simple C++ TBAA"}
+!25 = !DILocation(line: 5, column: 5, scope: !17)
+!26 = !DILocation(line: 5, column: 10, scope: !17)
+!27 = !DILocation(line: 6, column: 1, scope: !7)