Index: llvm/lib/CodeGen/CodeGenPrepare.cpp
===================================================================
--- llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -2605,6 +2605,7 @@
     /// trunc Opnd to Ty.
     TruncBuilder(Instruction *Opnd, Type *Ty) : TypePromotionAction(Opnd) {
       IRBuilder<> Builder(Opnd);
+      Builder.SetCurrentDebugLocation(DebugLoc());
       Val = Builder.CreateTrunc(Opnd, Ty, "promoted");
       LLVM_DEBUG(dbgs() << "Do: TruncBuilder: " << *Val << "\n");
     }
Index: llvm/test/Transforms/CodeGenPrepare/X86/promoted-trunc-loc.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/CodeGenPrepare/X86/promoted-trunc-loc.ll
@@ -0,0 +1,65 @@
+; RUN: opt < %s -codegenprepare -S -mtriple=x86_64-unknown-unknown | FileCheck %s
+
+; Make sure the promoted trunc doesn't get a debug location associated.
+; CHECK: %promoted = trunc i32 %or to i16
+
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.13.0"
+
+@b = global i16 0, align 2
+
+declare void @bar(i64)
+
+define i32 @foo(i16 %kkk) !dbg !6 {
+entry:
+  %t4 = load i16, i16* @b, align 2, !dbg !18
+  call void @llvm.dbg.value(metadata i16 %t4, metadata !9, metadata !DIExpression()), !dbg !18
+  %conv4 = zext i16 %t4 to i32, !dbg !19
+  call void @llvm.dbg.value(metadata i32 %conv4, metadata !11, metadata !DIExpression()), !dbg !19
+  %or = or i16 %kkk, %t4, !dbg !20
+  call void @llvm.dbg.value(metadata i16 %or, metadata !13, metadata !DIExpression()), !dbg !20
+  %c = sext i16 %or to i64, !dbg !21
+  call void @llvm.dbg.value(metadata i64 %c, metadata !14, metadata !DIExpression()), !dbg !21
+  call void @bar(i64 %c), !dbg !22
+  %t5 = and i16 %or, 5, !dbg !23
+  call void @llvm.dbg.value(metadata i16 %t5, metadata !16, metadata !DIExpression()), !dbg !23
+  %z = zext i16 %t5 to i32, !dbg !24
+  call void @llvm.dbg.value(metadata i32 %z, metadata !17, metadata !DIExpression()), !dbg !24
+  ret i32 %z, !dbg !25
+}
+
+; Function Attrs: nounwind readnone speculatable willreturn
+declare void @llvm.dbg.value(metadata, metadata, metadata) #0
+
+attributes #0 = { nounwind readnone speculatable willreturn }
+
+!llvm.dbg.cu = !{!0}
+!llvm.debugify = !{!3, !4}
+!llvm.module.flags = !{!5}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C, file: !1, producer: "debugify", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
+!1 = !DIFile(filename: "../../llvm-project/llvm/test/Transforms/CodeGenPrepare/X86/multi-extension.ll", directory: "/")
+!2 = !{}
+!3 = !{i32 8}
+!4 = !{i32 6}
+!5 = !{i32 2, !"Debug Info Version", i32 3}
+!6 = distinct !DISubprogram(name: "foo", linkageName: "foo", scope: null, file: !1, line: 1, type: !7, scopeLine: 1, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !8)
+!7 = !DISubroutineType(types: !2)
+!8 = !{!9, !11, !13, !14, !16, !17}
+!9 = !DILocalVariable(name: "1", scope: !6, file: !1, line: 1, type: !10)
+!10 = !DIBasicType(name: "ty16", size: 16, encoding: DW_ATE_unsigned)
+!11 = !DILocalVariable(name: "2", scope: !6, file: !1, line: 2, type: !12)
+!12 = !DIBasicType(name: "ty32", size: 32, encoding: DW_ATE_unsigned)
+!13 = !DILocalVariable(name: "3", scope: !6, file: !1, line: 3, type: !10)
+!14 = !DILocalVariable(name: "4", scope: !6, file: !1, line: 4, type: !15)
+!15 = !DIBasicType(name: "ty64", size: 64, encoding: DW_ATE_unsigned)
+!16 = !DILocalVariable(name: "5", scope: !6, file: !1, line: 6, type: !10)
+!17 = !DILocalVariable(name: "6", scope: !6, file: !1, line: 7, type: !12)
+!18 = !DILocation(line: 1, column: 1, scope: !6)
+!19 = !DILocation(line: 2, column: 1, scope: !6)
+!20 = !DILocation(line: 3, column: 1, scope: !6)
+!21 = !DILocation(line: 4, column: 1, scope: !6)
+!22 = !DILocation(line: 5, column: 1, scope: !6)
+!23 = !DILocation(line: 6, column: 1, scope: !6)
+!24 = !DILocation(line: 7, column: 1, scope: !6)
+!25 = !DILocation(line: 8, column: 1, scope: !6)