Index: llvm/trunk/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
===================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
@@ -998,8 +998,9 @@
     // that this code is not reachable.  We do this instead of inserting
     // an unreachable instruction directly because we cannot modify the
     // CFG.
-    new StoreInst(UndefValue::get(LI.getType()),
-                  Constant::getNullValue(Op->getType()), &LI);
+    StoreInst *SI = new StoreInst(UndefValue::get(LI.getType()),
+                                  Constant::getNullValue(Op->getType()), &LI);
+    SI->setDebugLoc(LI.getDebugLoc());
     return replaceInstUsesWith(LI, UndefValue::get(LI.getType()));
   }
 
Index: llvm/trunk/lib/Transforms/Scalar/GVN.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Scalar/GVN.cpp
+++ llvm/trunk/lib/Transforms/Scalar/GVN.cpp
@@ -1168,6 +1168,7 @@
                                  LI->isVolatile(), LI->getAlignment(),
                                  LI->getOrdering(), LI->getSyncScopeID(),
                                  UnavailablePred->getTerminator());
+    NewLoad->setDebugLoc(LI->getDebugLoc());
 
     // Transfer the old load's AA tags to the new load.
     AAMDNodes Tags;
Index: llvm/trunk/test/Transforms/GVN/PRE/2017-06-28-pre-load-dbgloc.ll
===================================================================
--- llvm/trunk/test/Transforms/GVN/PRE/2017-06-28-pre-load-dbgloc.ll
+++ llvm/trunk/test/Transforms/GVN/PRE/2017-06-28-pre-load-dbgloc.ll
@@ -0,0 +1,79 @@
+; This test checks if debug loc is propagated to load/store created by GVN/Instcombine.
+; RUN: opt < %s -gvn -S | FileCheck %s --check-prefixes=ALL,GVN
+; RUN: opt < %s -gvn -instcombine -S | FileCheck %s --check-prefixes=ALL,INSTCOMBINE
+
+; struct node {
+;  int  *v;
+; struct desc *descs;
+; };
+
+; struct desc {
+;  struct node *node;
+; };
+
+; extern int bar(void *v, void* n);
+
+; int test(struct desc *desc)
+; {
+;  void *v, *n;
+;  v = !desc ? ((void *)0) : desc->node->v;  // Line 15
+;  n = &desc->node->descs[0];                // Line 16
+;  return bar(v, n);
+; }
+
+; Line 16, Column 13:
+;   n = &desc->node->descs[0];
+;              ^
+
+target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
+target triple = "aarch64--linux-gnu"
+
+%struct.desc = type { %struct.node* }
+%struct.node = type { i32*, %struct.desc* }
+
+define i32 @test(%struct.desc* readonly %desc) local_unnamed_addr #0 !dbg !4 {
+entry:
+  %tobool = icmp eq %struct.desc* %desc, null
+  br i1 %tobool, label %cond.end, label %cond.false, !dbg !9
+; ALL: br i1 %tobool, label %entry.cond.end_crit_edge, label %cond.false, !dbg [[LOC_15_6:![0-9]+]]
+; ALL: entry.cond.end_crit_edge:
+; GVN: %.pre = load %struct.node*, %struct.node** null, align 8, !dbg [[LOC_16_13:![0-9]+]]
+; INSTCOMBINE:store %struct.node* undef, %struct.node** null, align 536870912, !dbg [[LOC_16_13:![0-9]+]]
+
+cond.false:
+  %0 = bitcast %struct.desc* %desc to i8***, !dbg !11
+  %1 = load i8**, i8*** %0, align 8, !dbg !11
+  %2 = load i8*, i8** %1, align 8
+  br label %cond.end, !dbg !9
+
+cond.end:
+  %3 = phi i8* [ %2, %cond.false ], [ null, %entry ], !dbg !9
+  %node2 = getelementptr inbounds %struct.desc, %struct.desc* %desc, i64 0, i32 0
+  %4 = load %struct.node*, %struct.node** %node2, align 8, !dbg !10
+  %descs = getelementptr inbounds %struct.node, %struct.node* %4, i64 0, i32 1
+  %5 = bitcast %struct.desc** %descs to i8**
+  %6 = load i8*, i8** %5, align 8
+  %call = tail call i32 @bar(i8* %3, i8* %6)
+  ret i32 %call
+}
+
+declare i32 @bar(i8*, i8*) local_unnamed_addr #1
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!2, !3}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, emissionKind: FullDebug)
+!1 = !DIFile(filename: "test.c", directory: ".")
+!2 = !{i32 2, !"Dwarf Version", i32 4}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!4 = distinct !DISubprogram(name: "test", scope: !1, file: !1, line: 12, type: !5, isLocal: false, isDefinition: true, scopeLine: 13, flags: DIFlagPrototyped, isOptimized: true, unit: !0, variables: !8)
+!5 = !DISubroutineType(types: !6)
+!6 = !{!7}
+!7 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!8 = !{}
+!9 = !DILocation(line: 15, column: 6, scope: !4)
+!10 = !DILocation(line: 16, column: 13, scope: !4)
+!11 = !DILocation(line: 15, column: 34, scope: !4)
+
+;ALL: [[SCOPE:![0-9]+]] = distinct  !DISubprogram(name: "test",{{.*}}
+;ALL: [[LOC_15_6]] = !DILocation(line: 15, column: 6, scope: [[SCOPE]])
+;ALL: [[LOC_16_13]] = !DILocation(line: 16, column: 13, scope: [[SCOPE]])
Index: llvm/trunk/test/Transforms/GVN/PRE/phi-translate.ll
===================================================================
--- llvm/trunk/test/Transforms/GVN/PRE/phi-translate.ll
+++ llvm/trunk/test/Transforms/GVN/PRE/phi-translate.ll
@@ -6,12 +6,12 @@
 ; CHECK: entry.end_crit_edge:
 ; CHECK: %[[INDEX:[a-z0-9.]+]] = sext i32 %x to i64{{$}}
 ; CHECK: %[[ADDRESS:[a-z0-9.]+]] = getelementptr [100 x i32], [100 x i32]* @G, i64 0, i64 %[[INDEX]]{{$}}
-; CHECK:   %n.pre = load i32, i32* %[[ADDRESS]]{{$}}
+; CHECK:   %n.pre = load i32, i32* %[[ADDRESS]], !dbg [[N_LOC:![0-9]+]]
 ; CHECK: br label %end
 ; CHECK: then:
 ; CHECK:   store i32 %z
 ; CHECK: end:
-; CHECK:   %n = phi i32 [ %n.pre, %entry.end_crit_edge ], [ %z, %then ], !dbg [[N_LOC:![0-9]+]]
+; CHECK:   %n = phi i32 [ %n.pre, %entry.end_crit_edge ], [ %z, %then ], !dbg [[N_LOC]]
 ; CHECK:   ret i32 %n
 
 ; CHECK: [[N_LOC]] = !DILocation(line: 47, column: 1, scope: !{{.*}})