Index: lib/CodeGen/CodeGenPrepare.cpp
===================================================================
--- lib/CodeGen/CodeGenPrepare.cpp
+++ lib/CodeGen/CodeGenPrepare.cpp
@@ -2956,7 +2956,7 @@
   // get through it and this method should not be called.
   Instruction *ExtOpnd = cast<Instruction>(Ext->getOperand(0));
   CreatedInstsCost = 0;
-  if (!ExtOpnd->hasOneUse()) {
+  if (!ExtOpnd->hasOneUse() || ExtOpnd->isUsedByMetadata()) {
     // ExtOpnd will be promoted.
     // All its uses, but Ext, will need to use a truncated value of the
     // promoted version.
Index: test/CodeGen/X86/metadata-trunc.ll
===================================================================
--- /dev/null
+++ test/CodeGen/X86/metadata-trunc.ll
@@ -0,0 +1,34 @@
+; RUN: opt -codegenprepare %s -S | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+declare void @llvm.dbg.value(metadata, i64, metadata, metadata)
+define void @isLegalUTF8Sequence() {
+entry:
+  %0 = load i8, i8* undef, align 1, !tbaa !9
+  %conv = sext i8 %0 to i32
+  %add = add nsw i32 %conv, 1, !dbg !16
+; CHECK-NOT: tail call void @llvm.dbg.value(metadata i64
+; CHECK: tail call void @llvm.dbg.value(metadata i32
+  tail call void @llvm.dbg.value(metadata i32 %add, i64 0, metadata !13, metadata !15), !dbg !16
+  %conv1 = sext i32 %add to i64
+  ret void
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!8}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 3.9.0 (https://github.com/llvm-mirror/clang 89dda3855cda574f355e6defa1d77bdae5053994) (llvm/trunk 257826)", isOptimized: true, runtimeVersion: 0, emissionKind: 1, subprograms: !5)
+!1 = !DIFile(filename: "none", directory: ".")
+!5 = !{!6}
+!6 = distinct !DISubprogram(name: "isLegalUTF8Sequence", scope: !1, file: !1, line: 386, type: !7, isLocal: false, isDefinition: true, scopeLine: 386, flags: DIFlagPrototyped, isOptimized: true)
+!7 = distinct !DISubroutineType(types: null)
+!8 = !{i32 2, !"Debug Info Version", i32 3}
+!9 = !{!10, !10, i64 0}
+!10 = !{!"omnipotent char", !11, i64 0}
+!11 = !{!"Simple C/C++ TBAA"}
+!13 = !DILocalVariable(name: "length", scope: !6, file: !1, line: 387, type: !14)
+!14 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
+!15 = !DIExpression()
+!16 = !DILocation(line: 387, column: 9, scope: !6)