diff --git a/compiler/elf_writer_mclinker.cc b/compiler/elf_writer_mclinker.cc
new file mode 100644
index 0000000..472a606
--- /dev/null
+++ b/compiler/elf_writer_mclinker.cc
@@ -0,0 +1,401 @@
+/*
+ * Copyright (C) 2012 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.
+ */
+
+#include "elf_writer_mclinker.h"
+
+#include <llvm/Support/TargetSelect.h>
+
+#include <mcld/Environment.h>
+#include <mcld/IRBuilder.h>
+#include <mcld/Linker.h>
+#include <mcld/LinkerConfig.h>
+#include <mcld/MC/ZOption.h>
+#include <mcld/Module.h>
+#include <mcld/Support/Path.h>
+#include <mcld/Support/TargetSelect.h>
+
+#include "base/unix_file/fd_file.h"
+#include "class_linker.h"
+#include "dex_method_iterator.h"
+#include "driver/compiler_driver.h"
+#include "elf_file.h"
+#include "globals.h"
+#include "mirror/abstract_method.h"
+#include "mirror/abstract_method-inl.h"
+#include "mirror/object-inl.h"
+#include "scoped_thread_state_change.h"
+
+namespace art {
+
+ElfWriterMclinker::ElfWriterMclinker(const CompilerDriver& driver, File* elf_file)
+  : ElfWriter(driver, elf_file), oat_input_(NULL) {}
+
+ElfWriterMclinker::~ElfWriterMclinker() {}
+
+bool ElfWriterMclinker::Create(File* elf_file,
+                               std::vector<uint8_t>& oat_contents,
+                               const std::vector<const DexFile*>& dex_files,
+                               const std::string& android_root,
+                               bool is_host,
+                               const CompilerDriver& driver) {
+  ElfWriterMclinker elf_writer(driver, elf_file);
+  return elf_writer.Write(oat_contents, dex_files, android_root, is_host);
+}
+
+bool ElfWriterMclinker::Write(std::vector<uint8_t>& oat_contents,
+                              const std::vector<const DexFile*>& dex_files,
+                              const std::string& android_root,
+                              bool is_host) {
+  Init();
+  AddOatInput(oat_contents);
+#if defined(ART_USE_PORTABLE_COMPILER)
+  AddMethodInputs(dex_files);
+  AddRuntimeInputs(android_root, is_host);
+#endif
+  if (!Link()) {
+    return false;
+  }
+#if defined(ART_USE_PORTABLE_COMPILER)
+  FixupOatMethodOffsets(dex_files);
+#endif
+  return true;
+}
+
+static void InitializeLLVM() {
+  // TODO: this is lifted from art's compiler_llvm.cc, should be factored out
+  if (kIsTargetBuild) {
+    llvm::InitializeNativeTarget();
+    // TODO: odd that there is no InitializeNativeTargetMC?
+  } else {
+    llvm::InitializeAllTargets();
+    llvm::InitializeAllTargetMCs();
+  }
+}
+
+void ElfWriterMclinker::Init() {
+  std::string target_triple;
+  std::string target_cpu;
+  std::string target_attr;
+  CompilerDriver::InstructionSetToLLVMTarget(compiler_driver_->GetInstructionSet(),
+                                             target_triple,
+                                             target_cpu,
+                                             target_attr);
+
+  // Based on mclinker's llvm-mcld.cpp main() and LinkerTest
+  //
+  // TODO: LinkerTest uses mcld::Initialize(), but it does an
+  // llvm::InitializeAllTargets, which we don't want. Basically we
+  // want mcld::InitializeNative, but it doesn't exist yet, so we
+  // inline the minimal we need here.
+  InitializeLLVM();
+  mcld::InitializeAllTargets();
+  mcld::InitializeAllLinkers();
+  mcld::InitializeAllEmulations();
+  mcld::InitializeAllDiagnostics();
+
+  linker_config_.reset(new mcld::LinkerConfig(target_triple));
+  CHECK(linker_config_.get() != NULL);
+  linker_config_->setCodeGenType(mcld::LinkerConfig::DynObj);
+  linker_config_->options().setSOName(elf_file_->GetPath());
+
+  // error on undefined symbols.
+  // TODO: should this just be set if kIsDebugBuild?
+  linker_config_->options().setNoUndefined(true);
+
+  if (compiler_driver_->GetInstructionSet() == kMips) {
+     // MCLinker defaults MIPS section alignment to 0x10000, not
+     // 0x1000.  The ABI says this is because the max page size is
+     // general is 64k but that isn't true on Android.
+     mcld::ZOption z_option;
+     z_option.setKind(mcld::ZOption::MaxPageSize);
+     z_option.setPageSize(kPageSize);
+     linker_config_->options().addZOption(z_option);
+  }
+
+  // TODO: Wire up mcld DiagnosticEngine to LOG?
+  linker_config_->options().setColor(false);
+  if (false) {
+    // enables some tracing of input file processing
+    linker_config_->options().setTrace(true);
+  }
+
+  // Based on alone::Linker::config
+  module_.reset(new mcld::Module(linker_config_->options().soname()));
+  CHECK(module_.get() != NULL);
+  ir_builder_.reset(new mcld::IRBuilder(*module_.get(), *linker_config_.get()));
+  CHECK(ir_builder_.get() != NULL);
+  linker_.reset(new mcld::Linker());
+  CHECK(linker_.get() != NULL);
+  linker_->config(*linker_config_.get());
+}
+
+void ElfWriterMclinker::AddOatInput(std::vector<uint8_t>& oat_contents) {
+  // Add an artificial memory input. Based on LinkerTest.
+  UniquePtr<OatFile> oat_file(OatFile::OpenMemory(oat_contents, elf_file_->GetPath()));
+  CHECK(oat_file.get() != NULL) << elf_file_->GetPath();
+
+  const char* oat_data_start = reinterpret_cast<const char*>(&oat_file->GetOatHeader());
+  const size_t oat_data_length = oat_file->GetOatHeader().GetExecutableOffset();
+  const char* oat_code_start = oat_data_start + oat_data_length;
+  const size_t oat_code_length = oat_file->Size() - oat_data_length;
+
+  // TODO: ownership of oat_input?
+  oat_input_ = ir_builder_->CreateInput("oat contents",
+                                        mcld::sys::fs::Path("oat contents path"),
+                                        mcld::Input::Object);
+  CHECK(oat_input_ != NULL);
+
+  // TODO: ownership of null_section?
+  mcld::LDSection* null_section = ir_builder_->CreateELFHeader(*oat_input_,
+                                                               "",
+                                                               mcld::LDFileFormat::Null,
+                                                               llvm::ELF::SHT_NULL,
+                                                               0);
+  CHECK(null_section != NULL);
+
+  // TODO: we should split readonly data from readonly executable
+  // code like .oat does.  We need to control section layout with
+  // linker script like functionality to guarantee references
+  // between sections maintain relative position which isn't
+  // possible right now with the mclinker APIs.
+  CHECK(oat_code_start != NULL);
+
+  // we need to ensure that oatdata is page aligned so when we
+  // fixup the segment load addresses, they remain page aligned.
+  uint32_t alignment = kPageSize;
+
+  // TODO: ownership of text_section?
+  mcld::LDSection* text_section = ir_builder_->CreateELFHeader(*oat_input_,
+                                                               ".text",
+                                                               llvm::ELF::SHT_PROGBITS,
+                                                               llvm::ELF::SHF_EXECINSTR
+                                                               | llvm::ELF::SHF_ALLOC,
+                                                               alignment);
+  CHECK(text_section != NULL);
+
+  mcld::SectionData* text_sectiondata = ir_builder_->CreateSectionData(*text_section);
+  CHECK(text_sectiondata != NULL);
+
+  // TODO: why does IRBuilder::CreateRegion take a non-const pointer?
+  mcld::Fragment* text_fragment = ir_builder_->CreateRegion(const_cast<char*>(oat_data_start),
+                                                            oat_file->Size());
+  CHECK(text_fragment != NULL);
+  ir_builder_->AppendFragment(*text_fragment, *text_sectiondata);
+
+  ir_builder_->AddSymbol(*oat_input_,
+                         "oatdata",
+                         mcld::ResolveInfo::Object,
+                         mcld::ResolveInfo::Define,
+                         mcld::ResolveInfo::Global,
+                         oat_data_length,  // size
+                         0,                // offset
+                         text_section);
+
+  ir_builder_->AddSymbol(*oat_input_,
+                         "oatexec",
+                         mcld::ResolveInfo::Function,
+                         mcld::ResolveInfo::Define,
+                         mcld::ResolveInfo::Global,
+                         oat_code_length,  // size
+                         oat_data_length,  // offset
+                         text_section);
+
+  ir_builder_->AddSymbol(*oat_input_,
+                         "oatlastword",
+                         mcld::ResolveInfo::Object,
+                         mcld::ResolveInfo::Define,
+                         mcld::ResolveInfo::Global,
+                         0,                // size
+                         // subtract a word so symbol is within section
+                         (oat_data_length + oat_code_length) - sizeof(uint32_t),  // offset
+                         text_section);
+}
+
+#if defined(ART_USE_PORTABLE_COMPILER)
+void ElfWriterMclinker::AddMethodInputs(const std::vector<const DexFile*>& dex_files) {
+  DCHECK(oat_input_ != NULL);
+
+  DexMethodIterator it(dex_files);
+  while (it.HasNext()) {
+    const DexFile& dex_file = it.GetDexFile();
+    uint32_t method_idx = it.GetMemberIndex();
+    const CompiledMethod* compiled_method =
+      compiler_driver_->GetCompiledMethod(MethodReference(&dex_file, method_idx));
+    if (compiled_method != NULL) {
+      AddCompiledCodeInput(*compiled_method);
+    }
+    it.Next();
+  }
+  added_symbols_.clear();
+}
+
+void ElfWriterMclinker::AddCompiledCodeInput(const CompiledCode& compiled_code) {
+  // Check if we've seen this compiled code before. If so skip
+  // it. This can happen for reused code such as invoke stubs.
+  const std::string& symbol = compiled_code.GetSymbol();
+  SafeMap<const std::string*, const std::string*>::iterator it = added_symbols_.find(&symbol);
+  if (it != added_symbols_.end()) {
+    return;
+  }
+  added_symbols_.Put(&symbol, &symbol);
+
+  // Add input to supply code for symbol
+  const std::vector<uint8_t>& code = compiled_code.GetCode();
+  // TODO: ownership of code_input?
+  // TODO: why does IRBuilder::ReadInput take a non-const pointer?
+  mcld::Input* code_input = ir_builder_->ReadInput(symbol,
+                                                   const_cast<uint8_t*>(&code[0]),
+                                                   code.size());
+  CHECK(code_input != NULL);
+}
+
+void ElfWriterMclinker::AddRuntimeInputs(const std::string& android_root, bool is_host) {
+  std::string libart_so(android_root);
+  libart_so += kIsDebugBuild ? "/lib/libartd.so" : "/lib/libart.so";
+  // TODO: ownership of libart_so_input?
+  mcld::Input* libart_so_input = ir_builder_->ReadInput(libart_so, libart_so);
+  CHECK(libart_so_input != NULL);
+
+  std::string host_prebuilt_dir("prebuilts/gcc/linux-x86/host/i686-linux-glibc2.7-4.6");
+
+  std::string compiler_runtime_lib;
+  if (is_host) {
+    compiler_runtime_lib += host_prebuilt_dir;
+    compiler_runtime_lib += "/lib/gcc/i686-linux/4.6.x-google/libgcc.a";
+  } else {
+    compiler_runtime_lib += android_root;
+    compiler_runtime_lib += "/lib/libcompiler_rt.a";
+  }
+  // TODO: ownership of compiler_runtime_lib_input?
+  mcld::Input* compiler_runtime_lib_input = ir_builder_->ReadInput(compiler_runtime_lib,
+                                                                   compiler_runtime_lib);
+  CHECK(compiler_runtime_lib_input != NULL);
+
+  std::string libc_lib;
+  if (is_host) {
+    libc_lib += host_prebuilt_dir;
+    libc_lib += "/sysroot/usr/lib/libc.so.6";
+  } else {
+    libc_lib += android_root;
+    libc_lib += "/lib/libc.so";
+  }
+  // TODO: ownership of libc_lib_input?
+  mcld::Input* libc_lib_input_input = ir_builder_->ReadInput(libc_lib, libc_lib);
+  CHECK(libc_lib_input_input != NULL);
+
+  std::string libm_lib;
+  if (is_host) {
+    libm_lib += host_prebuilt_dir;
+    libm_lib += "/sysroot/usr/lib/libm.so";
+  } else {
+    libm_lib += android_root;
+    libm_lib += "/lib/libm.so";
+  }
+  // TODO: ownership of libm_lib_input?
+  mcld::Input* libm_lib_input_input = ir_builder_->ReadInput(libm_lib, libm_lib);
+  CHECK(libm_lib_input_input != NULL);
+
+}
+#endif
+
+bool ElfWriterMclinker::Link() {
+  // link inputs
+  if (!linker_->link(*module_.get(), *ir_builder_.get())) {
+    LOG(ERROR) << "Failed to link " << elf_file_->GetPath();
+    return false;
+  }
+
+  // emit linked output
+  // TODO: avoid dup of fd by fixing Linker::emit to not close the argument fd.
+  int fd = dup(elf_file_->Fd());
+  if (fd == -1) {
+    PLOG(ERROR) << "Failed to dup file descriptor for " << elf_file_->GetPath();
+    return false;
+  }
+  if (!linker_->emit(fd)) {
+    LOG(ERROR) << "Failed to emit " << elf_file_->GetPath();
+    return false;
+  }
+  mcld::Finalize();
+  LOG(INFO) << "ELF file written successfully: " << elf_file_->GetPath();
+  return true;
+}
+
+#if defined(ART_USE_PORTABLE_COMPILER)
+void ElfWriterMclinker::FixupOatMethodOffsets(const std::vector<const DexFile*>& dex_files) {
+  UniquePtr<ElfFile> elf_file(ElfFile::Open(elf_file_, true, false));
+  CHECK(elf_file.get() != NULL) << elf_file_->GetPath();
+
+  llvm::ELF::Elf32_Addr oatdata_address = GetOatDataAddress(elf_file.get());
+  DexMethodIterator it(dex_files);
+  while (it.HasNext()) {
+    const DexFile& dex_file = it.GetDexFile();
+    uint32_t method_idx = it.GetMemberIndex();
+    InvokeType invoke_type = it.GetInvokeType();
+    mirror::AbstractMethod* method = NULL;
+    if (compiler_driver_->IsImage()) {
+      ClassLinker* linker = Runtime::Current()->GetClassLinker();
+      mirror::DexCache* dex_cache = linker->FindDexCache(dex_file);
+      // Unchecked as we hold mutator_lock_ on entry.
+      ScopedObjectAccessUnchecked soa(Thread::Current());
+      method = linker->ResolveMethod(dex_file, method_idx, dex_cache, NULL, NULL, invoke_type);
+      CHECK(method != NULL);
+    }
+    const CompiledMethod* compiled_method =
+      compiler_driver_->GetCompiledMethod(MethodReference(&dex_file, method_idx));
+    if (compiled_method != NULL) {
+      uint32_t offset = FixupCompiledCodeOffset(*elf_file.get(), oatdata_address, *compiled_method);
+      // Don't overwrite static method trampoline
+      if (method != NULL &&
+          (!method->IsStatic() ||
+           method->IsConstructor() ||
+           method->GetDeclaringClass()->IsInitialized())) {
+        method->SetOatCodeOffset(offset);
+      }
+    }
+    it.Next();
+  }
+  symbol_to_compiled_code_offset_.clear();
+}
+
+uint32_t ElfWriterMclinker::FixupCompiledCodeOffset(ElfFile& elf_file,
+                                                    llvm::ELF::Elf32_Addr oatdata_address,
+                                                    const CompiledCode& compiled_code) {
+  const std::string& symbol = compiled_code.GetSymbol();
+  SafeMap<const std::string*, uint32_t>::iterator it = symbol_to_compiled_code_offset_.find(&symbol);
+  if (it != symbol_to_compiled_code_offset_.end()) {
+    return it->second;
+  }
+
+  llvm::ELF::Elf32_Addr compiled_code_address = elf_file.FindSymbolAddress(llvm::ELF::SHT_SYMTAB,
+                                                                           symbol,
+                                                                           true);
+  CHECK_NE(0U, compiled_code_address) << symbol;
+  CHECK_LT(oatdata_address, compiled_code_address) << symbol;
+  uint32_t compiled_code_offset = compiled_code_address - oatdata_address;
+  symbol_to_compiled_code_offset_.Put(&symbol, compiled_code_offset);
+
+  const std::vector<uint32_t>& offsets = compiled_code.GetOatdataOffsetsToCompliledCodeOffset();
+  for (uint32_t i = 0; i < offsets.size(); i++) {
+    uint32_t oatdata_offset = oatdata_address + offsets[i];
+    uint32_t* addr = reinterpret_cast<uint32_t*>(elf_file.Begin() + oatdata_offset);
+    *addr = compiled_code_offset;
+  }
+  return compiled_code_offset;
+}
+#endif
+
+}  // namespace art