Index: lib/CodeGen/TailDuplicator.cpp
===================================================================
--- lib/CodeGen/TailDuplicator.cpp
+++ lib/CodeGen/TailDuplicator.cpp
@@ -725,6 +725,7 @@
     if (PredTBB == NextBB && PredFBB == nullptr)
       PredTBB = nullptr;
 
+    auto DL = PredBB->findBranchDebugLoc();
     TII->removeBranch(*PredBB);
 
     if (!PredBB->isSuccessor(NewTarget))
@@ -735,7 +736,7 @@
     }
 
     if (PredTBB)
-      TII->insertBranch(*PredBB, PredTBB, PredFBB, PredCond, DebugLoc());
+      TII->insertBranch(*PredBB, PredTBB, PredFBB, PredCond, DL);
 
     TDBBs.push_back(PredBB);
   }
Index: test/CodeGen/X86/tail-dup-debugloc.ll
===================================================================
--- /dev/null
+++ test/CodeGen/X86/tail-dup-debugloc.ll
@@ -0,0 +1,56 @@
+; RUN: llc -stop-after=tailduplication -march=x86-64 < %s | FileCheck %s
+;
+; Check that DebugLoc attached to the branch instruction of 
+; 'while.cond1.preheader.lr.ph' survives after tailduplication pass.
+;
+; CHECK: [[DLOC:![0-9]+]] = !DILocation(line: 9, column: 5, scope: !{{[0-9]+}})
+; CHECK: [[VREG:%[^ ]+]] = COPY %rdi
+; CHECK: TEST64rr [[VREG]], [[VREG]]
+; CHECK-NEXT: JE_1 {{.+}}, debug-location [[DLOC]]
+; CHECK-NEXT: JMP_1 {{.+}}, debug-location [[DLOC]]
+
+target triple = "x86_64-unknown-linux-gnu"
+
+%struct.Node = type { %struct.Node* }
+
+define i32 @foo(%struct.Node* readonly %node, %struct.Node* readnone %root) !dbg !6 {
+entry:
+  %cmp = icmp eq %struct.Node* %node, %root, !dbg !8
+  br i1 %cmp, label %while.end4, label %while.cond1.preheader.lr.ph, !dbg !10
+
+while.cond1.preheader.lr.ph:                      ; preds = %entry
+  %tobool = icmp eq %struct.Node* %node, null
+  br i1 %tobool, label %while.cond1.preheader.us.preheader, label %while.body2.preheader, !dbg !11
+
+while.body2.preheader:                            ; preds = %while.cond1.preheader.lr.ph
+  br label %while.body2, !dbg !11
+
+while.cond1.preheader.us.preheader:               ; preds = %while.cond1.preheader.lr.ph
+  br label %while.cond1.preheader.us, !dbg !10
+
+while.cond1.preheader.us:                         ; preds = %while.cond1.preheader.us.preheader, %while.cond1.preheader.us
+  br label %while.cond1.preheader.us, !dbg !10
+
+while.body2:                                      ; preds = %while.body2.preheader, %while.body2
+  br label %while.body2, !dbg !11
+
+while.end4:                                       ; preds = %entry
+  ret i32 0, !dbg !12
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, isOptimized: true, emissionKind: LineTablesOnly)
+!1 = !DIFile(filename: "foo.c", directory: "b/")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{}
+!6 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 5, type: !7, isLocal: false, isDefinition: true, scopeLine: 5, flags: DIFlagPrototyped, isOptimized: true, unit: !0, variables: !2)
+!7 = !DISubroutineType(types: !2)
+!8 = !DILocation(line: 7, column: 15, scope: !9)
+!9 = !DILexicalBlockFile(scope: !6, file: !1, discriminator: 2)
+!10 = !DILocation(line: 7, column: 3, scope: !9)
+!11 = !DILocation(line: 9, column: 5, scope: !9)
+!12 = !DILocation(line: 14, column: 3, scope: !6)