diff --git a/llvm/lib/DebugInfo/CodeView/ByteStream.cpp b/llvm/lib/DebugInfo/CodeView/ByteStream.cpp
new file mode 100644
index 0000000..879343a
--- /dev/null
+++ b/llvm/lib/DebugInfo/CodeView/ByteStream.cpp
@@ -0,0 +1,72 @@
+//===- ByteStream.cpp - Reads stream data from a byte sequence ------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/DebugInfo/CodeView/ByteStream.h"
+#include "llvm/DebugInfo/CodeView/CodeViewError.h"
+#include "llvm/DebugInfo/CodeView/StreamReader.h"
+#include <cstring>
+
+using namespace llvm;
+using namespace llvm::codeview;
+
+ByteStream::ByteStream() {}
+
+ByteStream::ByteStream(MutableArrayRef<uint8_t> Bytes) { initialize(Bytes); }
+
+ByteStream::ByteStream(uint32_t Length) { initialize(Length); }
+
+ByteStream::~ByteStream() { reset(); }
+
+void ByteStream::reset() {
+  Ownership.reset();
+  Data = MutableArrayRef<uint8_t>();
+}
+
+void ByteStream::initialize(MutableArrayRef<uint8_t> Bytes) {
+  reset();
+  Data = Bytes;
+}
+
+void ByteStream::initialize(uint32_t Length) {
+  reset();
+  if (Length > 0)
+    Data = MutableArrayRef<uint8_t>(new uint8_t[Length], Length);
+  Ownership.reset(Data.data());
+}
+
+Error ByteStream::initialize(StreamReader &Reader, uint32_t Length) {
+  initialize(Length);
+  auto EC = Reader.readBytes(Data);
+  if (EC)
+    reset();
+  return EC;
+}
+
+Error ByteStream::readBytes(uint32_t Offset,
+                            MutableArrayRef<uint8_t> Buffer) const {
+  if (Data.size() < Buffer.size() + Offset)
+    return make_error<CodeViewError>(cv_error_code::insufficient_buffer);
+  ::memcpy(Buffer.data(), Data.data() + Offset, Buffer.size());
+  return Error::success();
+}
+
+Error ByteStream::getArrayRef(uint32_t Offset, ArrayRef<uint8_t> &Buffer,
+                              uint32_t Length) const {
+  if (Data.size() < Length + Offset)
+    return make_error<CodeViewError>(cv_error_code::insufficient_buffer);
+  Buffer = Data.slice(Offset, Length);
+  return Error::success();
+}
+
+uint32_t ByteStream::getLength() const { return Data.size(); }
+
+StringRef ByteStream::str() const {
+  const char *CharData = reinterpret_cast<const char *>(Data.data());
+  return StringRef(CharData, Data.size());
+}