Index: lib/Bitcode/Writer/BitcodeWriter.cpp
===================================================================
--- lib/Bitcode/Writer/BitcodeWriter.cpp
+++ lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -278,10 +278,10 @@
           StringRef Val = Attr.getValueAsString();
 
           Record.push_back(Val.empty() ? 3 : 4);
-          Record.append(Kind.begin(), Kind.end());
+          Record.append((uint8_t*)Kind.begin(), (uint8_t*)Kind.end());
           Record.push_back(0);
           if (!Val.empty()) {
-            Record.append(Val.begin(), Val.end());
+            Record.append((uint8_t*)Val.begin(), (uint8_t*)Val.end());
             Record.push_back(0);
           }
         }
@@ -784,7 +784,7 @@
       }
 
       // Code: [strchar x N]
-      Record.append(MDS->begin(), MDS->end());
+      Record.append((uint8_t *)MDS->begin(), (uint8_t *)MDS->end());
 
       // Emit the finished record.
       Stream.EmitRecord(bitc::METADATA_STRING, Record, MDSAbbrev);
@@ -887,7 +887,7 @@
   for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
     Record.push_back(MDKindID);
     StringRef KName = Names[MDKindID];
-    Record.append(KName.begin(), KName.end());
+    Record.append((uint8_t*)KName.begin(), (uint8_t*)KName.end());
 
     Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
     Record.clear();
Index: test/Bitcode/unicode.ll
===================================================================
--- /dev/null
+++ test/Bitcode/unicode.ll
@@ -0,0 +1,11 @@
+; RUN: llvm-as < %s | llvm-dis | FileCheck %s
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!5}
+
+!0 = metadata !{metadata !"0x11\0012\00clang version ☃\001\00\000\00\000", metadata !4, metadata !2, metadata !2, metadata !2, metadata !2, null} ; [ DW_TAG_compile_unit ]
+; CHECK: "0x11\0012\00clang version \E2\98\83\001\00\000\00\000"
+!2 = metadata !{}
+!3 = metadata !{metadata !"0x29", metadata !4} ; [ DW_TAG_file_type ]
+!4 = metadata !{metadata !"empty.c", metadata !"/tmp"}
+!5 = metadata !{i32 1, metadata !"Debug Info Version", i32 2}