diff --git a/dexlayout/dex_writer.h b/dexlayout/dex_writer.h
new file mode 100644
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--- /dev/null
+++ b/dexlayout/dex_writer.h
@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * Header file of an in-memory representation of DEX files.
+ */
+
+#ifndef ART_DEXLAYOUT_DEX_WRITER_H_
+#define ART_DEXLAYOUT_DEX_WRITER_H_
+
+#include "base/unix_file/fd_file.h"
+#include "dex_ir.h"
+#include "os.h"
+
+namespace art {
+
+class DexWriter {
+ public:
+  DexWriter(dex_ir::Header& header, const char* file_name) : header_(header),
+      dex_file_(OS::CreateEmptyFileWriteOnly(file_name)) { }
+
+  static void OutputDexFile(dex_ir::Header& header, const char* file_name);
+
+ private:
+  void WriteFile();
+
+  size_t Write(const void* buffer, size_t length, size_t offset);
+  size_t WriteSleb128(uint32_t value, size_t offset);
+  size_t WriteUleb128(uint32_t value, size_t offset);
+  size_t WriteEncodedValue(dex_ir::EncodedValue* encoded_value, size_t offset);
+  size_t WriteEncodedValueHeader(int8_t value_type, size_t value_arg, size_t offset);
+  size_t WriteEncodedArray(dex_ir::EncodedValueVector* values, size_t offset);
+  size_t WriteEncodedAnnotation(dex_ir::EncodedAnnotation* annotation, size_t offset);
+  size_t WriteEncodedFields(dex_ir::FieldItemVector* fields, size_t offset);
+  size_t WriteEncodedMethods(dex_ir::MethodItemVector* methods, size_t offset);
+
+  void WriteStrings();
+  void WriteTypes();
+  void WriteTypeLists();
+  void WriteProtos();
+  void WriteFields();
+  void WriteMethods();
+  void WriteEncodedArrays();
+  void WriteAnnotations();
+  void WriteAnnotationSets();
+  void WriteAnnotationSetRefs();
+  void WriteAnnotationsDirectories();
+  void WriteDebugInfoItems();
+  void WriteCodeItems();
+  void WriteClasses();
+  void WriteMapItem();
+  void WriteHeader();
+
+  dex_ir::Header& header_;
+  std::unique_ptr<File> dex_file_;
+
+  DISALLOW_COPY_AND_ASSIGN(DexWriter);
+};
+
+
+}  // namespace art
+
+#endif  // ART_DEXLAYOUT_DEX_WRITER_H_