Index: docs/Readers.rst
===================================================================
--- docs/Readers.rst
+++ docs/Readers.rst
@@ -10,8 +10,8 @@
 and create an `lld::File`:cpp:class: (which is a graph of Atoms)
 representing the object file.  A Reader inherits from
 `lld::Reader`:cpp:class: which lives in
-:file:`include/lld/ReaderWriter/Reader.h` and
-:file:`lib/ReaderWriter/Reader.cpp`.
+:file:`include/lld/Core/Reader.h` and
+:file:`lib/Core/Reader.cpp`.
 
 The Reader infrastructure for an object format ``Foo`` requires the
 following pieces in order to fit into lld:
Index: include/lld/Core/LinkingContext.h
===================================================================
--- include/lld/Core/LinkingContext.h
+++ include/lld/Core/LinkingContext.h
@@ -16,7 +16,7 @@
 #include "lld/Core/Parallel.h"
 #include "lld/Core/Reference.h"
 #include "lld/Core/range.h"
-#include "lld/ReaderWriter/Reader.h"
+#include "lld/Core/Reader.h"
 #include "llvm/Support/ErrorOr.h"
 #include "llvm/Support/raw_ostream.h"
 #include <string>
Index: include/lld/Core/Reader.h
===================================================================
--- /dev/null
+++ include/lld/Core/Reader.h
@@ -0,0 +1,170 @@
+//===- lld/Core/Reader.h - Abstract File Format Reading Interface ---------===//
+//
+//                             The LLVM Linker
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLD_CORE_READER_H
+#define LLD_CORE_READER_H
+
+#include "lld/Core/LLVM.h"
+#include "lld/Core/Reference.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/YAMLTraits.h"
+#include <functional>
+#include <memory>
+#include <vector>
+
+using llvm::sys::fs::file_magic;
+
+namespace llvm {
+namespace yaml {
+class IO;
+}
+}
+
+namespace lld {
+class ELFLinkingContext;
+class File;
+class LinkingContext;
+class PECOFFLinkingContext;
+class TargetHandlerBase;
+class MachOLinkingContext;
+
+/// \brief An abstract class for reading object files, library files, and
+/// executable files.
+///
+/// Each file format (e.g. ELF, mach-o, PECOFF, native, etc) have a concrete
+/// subclass of Reader.
+class Reader {
+public:
+  virtual ~Reader() {}
+
+  /// Sniffs the file to determine if this Reader can parse it.
+  /// The method is called with:
+  /// 1) the file_magic enumeration returned by identify_magic()
+  /// 2) the file extension (e.g. ".obj")
+  /// 3) the whole file content buffer if the above is not enough.
+  virtual bool canParse(file_magic magic, StringRef fileExtension,
+                        const MemoryBuffer &mb) const = 0;
+
+  /// \brief Parse a supplied buffer (already filled with the contents of a
+  /// file) and create a File object.
+  /// The resulting File object takes ownership of the MemoryBuffer.
+  virtual std::error_code
+  loadFile(std::unique_ptr<MemoryBuffer> mb, const class Registry &,
+           std::vector<std::unique_ptr<File>> &result) const = 0;
+};
+
+
+/// \brief An abstract class for handling alternate yaml representations
+/// of object files.
+///
+/// The YAML syntax allows "tags" which are used to specify the type of
+/// the YAML node.  In lld, top level YAML documents can be in many YAML
+/// representations (e.g mach-o encoded as yaml, etc).  A tag is used to
+/// specify which representation is used in the following YAML document.
+/// To work, there must be a YamlIOTaggedDocumentHandler registered that
+/// handles each tag type.
+class YamlIOTaggedDocumentHandler {
+public:
+  virtual ~YamlIOTaggedDocumentHandler();
+
+  /// This method is called on each registered YamlIOTaggedDocumentHandler
+  /// until one returns true.  If the subclass handles tag type !xyz, then
+  /// this method should call io.mapTag("!xzy") to see if that is the current
+  /// document type, and if so, process the rest of the document using
+  /// YAML I/O, then convert the result into an lld::File* and return it.
+  virtual bool handledDocTag(llvm::yaml::IO &io, const lld::File *&f) const = 0;
+};
+
+
+/// A registry to hold the list of currently registered Readers and
+/// tables which map Reference kind values to strings.
+/// The linker does not directly invoke Readers.  Instead, it registers
+/// Readers based on it configuration and command line options, then calls
+/// the Registry object to parse files.
+class Registry {
+public:
+  Registry();
+
+  /// Walk the list of registered Readers and find one that can parse the
+  /// supplied file and parse it.
+  std::error_code loadFile(std::unique_ptr<MemoryBuffer> mb,
+                           std::vector<std::unique_ptr<File>> &result) const;
+
+  /// Walk the list of registered kind tables to convert a Reference Kind
+  /// name to a value.
+  bool referenceKindFromString(StringRef inputStr, Reference::KindNamespace &ns,
+                               Reference::KindArch &a,
+                               Reference::KindValue &value) const;
+
+  /// Walk the list of registered kind tables to convert a Reference Kind
+  /// value to a string.
+  bool referenceKindToString(Reference::KindNamespace ns, Reference::KindArch a,
+                             Reference::KindValue value, StringRef &) const;
+
+  /// Walk the list of registered tag handlers and have the one that handles
+  /// the current document type process the yaml into an lld::File*.
+  bool handleTaggedDoc(llvm::yaml::IO &io, const lld::File *&file) const;
+
+  // These methods are called to dynamically add support for various file
+  // formats. The methods are also implemented in the appropriate lib*.a
+  // library, so that the code for handling a format is only linked in, if this
+  // method is used.  Any options that a Reader might need must be passed
+  // as parameters to the addSupport*() method.
+  void addSupportArchives(bool logLoading);
+  void addSupportYamlFiles();
+  void addSupportNativeObjects();
+  void addSupportCOFFObjects(PECOFFLinkingContext &);
+  void addSupportCOFFImportLibraries(PECOFFLinkingContext &);
+  void addSupportMachOObjects(MachOLinkingContext &);
+  void addSupportELFObjects(bool atomizeStrings, TargetHandlerBase *handler);
+  void addSupportELFDynamicSharedObjects(bool useShlibUndefines,
+                                         TargetHandlerBase *handler);
+
+  /// To convert between kind values and names, the registry walks the list
+  /// of registered kind tables. Each table is a zero terminated array of
+  /// KindStrings elements.
+  struct KindStrings {
+    Reference::KindValue  value;
+    StringRef             name;
+  };
+
+  /// A Reference Kind value is a tuple of <namespace, arch, value>.  All
+  /// entries in a conversion table have the same <namespace, arch>.  The
+  /// array then contains the value/name pairs.
+  void addKindTable(Reference::KindNamespace ns, Reference::KindArch arch,
+                    const KindStrings array[]);
+
+
+private:
+  struct KindEntry {
+    Reference::KindNamespace  ns;
+    Reference::KindArch       arch;
+    const KindStrings        *array;
+  };
+
+  void add(std::unique_ptr<Reader>);
+  void add(std::unique_ptr<YamlIOTaggedDocumentHandler>);
+
+  std::vector<std::unique_ptr<Reader>>                       _readers;
+  std::vector<std::unique_ptr<YamlIOTaggedDocumentHandler>>  _yamlHandlers;
+  std::vector<KindEntry>                                     _kindEntries;
+};
+
+// Utilities for building a KindString table.  For instance:
+//   static const Registry::KindStrings table[] = {
+//      LLD_KIND_STRING_ENTRY(R_VAX_ADDR16),
+//      LLD_KIND_STRING_ENTRY(R_VAX_DATA16),
+//      LLD_KIND_STRING_END
+//   };
+#define LLD_KIND_STRING_ENTRY(name) { name, #name }
+#define LLD_KIND_STRING_END         { 0,    "" }
+
+} // end namespace lld
+
+#endif
Index: include/lld/Core/Writer.h
===================================================================
--- /dev/null
+++ include/lld/Core/Writer.h
@@ -0,0 +1,52 @@
+//===- lld/Core/Writer.h - Abstract File Format Interface -----------------===//
+//
+//                             The LLVM Linker
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLD_CORE_WRITER_H
+#define LLD_CORE_WRITER_H
+
+#include "lld/Core/LLVM.h"
+#include <memory>
+#include <vector>
+
+namespace lld {
+class File;
+class ELFLinkingContext;
+class MachOLinkingContext;
+class PECOFFLinkingContext;
+class LinkingContext;
+class TargetHandlerBase;
+
+/// \brief The Writer is an abstract class for writing object files, shared
+/// library files, and executable files.  Each file format (e.g. ELF, mach-o,
+/// PECOFF, native, etc) have a concrete subclass of Writer.
+class Writer {
+public:
+  virtual ~Writer();
+
+  /// \brief Write a file from the supplied File object
+  virtual std::error_code writeFile(const File &linkedFile, StringRef path) = 0;
+
+  /// \brief This method is called by Core Linking to give the Writer a chance
+  /// to add file format specific "files" to set of files to be linked. This is
+  /// how file format specific atoms can be added to the link.
+  virtual bool createImplicitFiles(std::vector<std::unique_ptr<File> > &);
+
+protected:
+  // only concrete subclasses can be instantiated
+  Writer();
+};
+
+std::unique_ptr<Writer> createWriterELF(TargetHandlerBase *handler);
+std::unique_ptr<Writer> createWriterMachO(const MachOLinkingContext &);
+std::unique_ptr<Writer> createWriterPECOFF(const PECOFFLinkingContext &);
+std::unique_ptr<Writer> createWriterNative(const LinkingContext &);
+std::unique_ptr<Writer> createWriterYAML(const LinkingContext &);
+} // end namespace lld
+
+#endif
Index: include/lld/Passes/LayoutPass.h
===================================================================
--- include/lld/Passes/LayoutPass.h
+++ include/lld/Passes/LayoutPass.h
@@ -12,7 +12,7 @@
 
 #include "lld/Core/File.h"
 #include "lld/Core/Pass.h"
-#include "lld/ReaderWriter/Reader.h"
+#include "lld/Core/Reader.h"
 #include "llvm/ADT/DenseMap.h"
 #include <map>
 #include <string>
Index: include/lld/ReaderWriter/CoreLinkingContext.h
===================================================================
--- include/lld/ReaderWriter/CoreLinkingContext.h
+++ include/lld/ReaderWriter/CoreLinkingContext.h
@@ -11,8 +11,8 @@
 #define LLD_READER_WRITER_CORE_LINKER_CONTEXT_H
 
 #include "lld/Core/LinkingContext.h"
-#include "lld/ReaderWriter/Reader.h"
-#include "lld/ReaderWriter/Writer.h"
+#include "lld/Core/Reader.h"
+#include "lld/Core/Writer.h"
 #include "llvm/Support/ErrorHandling.h"
 
 namespace lld {
Index: include/lld/ReaderWriter/ELFLinkingContext.h
===================================================================
--- include/lld/ReaderWriter/ELFLinkingContext.h
+++ include/lld/ReaderWriter/ELFLinkingContext.h
@@ -15,8 +15,8 @@
 #include "lld/Core/PassManager.h"
 #include "lld/Core/STDExtras.h"
 #include "lld/Core/range.h"
-#include "lld/ReaderWriter/Reader.h"
-#include "lld/ReaderWriter/Writer.h"
+#include "lld/Core/Reader.h"
+#include "lld/Core/Writer.h"
 #include "llvm/ADT/StringSet.h"
 #include "llvm/ADT/Triple.h"
 #include "llvm/Object/ELF.h"
Index: include/lld/ReaderWriter/MachOLinkingContext.h
===================================================================
--- include/lld/ReaderWriter/MachOLinkingContext.h
+++ include/lld/ReaderWriter/MachOLinkingContext.h
@@ -11,8 +11,8 @@
 #define LLD_READER_WRITER_MACHO_LINKING_CONTEXT_H
 
 #include "lld/Core/LinkingContext.h"
-#include "lld/ReaderWriter/Reader.h"
-#include "lld/ReaderWriter/Writer.h"
+#include "lld/Core/Reader.h"
+#include "lld/Core/Writer.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringSet.h"
 #include "llvm/Support/ErrorHandling.h"
Index: include/lld/ReaderWriter/PECOFFLinkingContext.h
===================================================================
--- include/lld/ReaderWriter/PECOFFLinkingContext.h
+++ include/lld/ReaderWriter/PECOFFLinkingContext.h
@@ -11,8 +11,8 @@
 #define LLD_READER_WRITER_PECOFF_LINKING_CONTEXT_H
 
 #include "lld/Core/LinkingContext.h"
-#include "lld/ReaderWriter/Reader.h"
-#include "lld/ReaderWriter/Writer.h"
+#include "lld/Core/Reader.h"
+#include "lld/Core/Writer.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/Support/Allocator.h"
 #include "llvm/Support/COFF.h"
Index: include/lld/ReaderWriter/Reader.h
===================================================================
--- include/lld/ReaderWriter/Reader.h
+++ /dev/null
@@ -1,170 +0,0 @@
-//===- lld/ReaderWriter/Reader.h - Abstract File Format Reading Interface -===//
-//
-//                             The LLVM Linker
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef LLD_READER_WRITER_READER_H
-#define LLD_READER_WRITER_READER_H
-
-#include "lld/Core/LLVM.h"
-#include "lld/Core/Reference.h"
-#include "llvm/Support/FileSystem.h"
-#include "llvm/Support/YAMLTraits.h"
-#include <functional>
-#include <memory>
-#include <vector>
-
-using llvm::sys::fs::file_magic;
-
-namespace llvm {
-namespace yaml {
-class IO;
-}
-}
-
-namespace lld {
-class ELFLinkingContext;
-class File;
-class LinkingContext;
-class PECOFFLinkingContext;
-class TargetHandlerBase;
-class MachOLinkingContext;
-
-/// \brief An abstract class for reading object files, library files, and
-/// executable files.
-///
-/// Each file format (e.g. ELF, mach-o, PECOFF, native, etc) have a concrete
-/// subclass of Reader.
-class Reader {
-public:
-  virtual ~Reader() {}
-
-  /// Sniffs the file to determine if this Reader can parse it.
-  /// The method is called with:
-  /// 1) the file_magic enumeration returned by identify_magic()
-  /// 2) the file extension (e.g. ".obj")
-  /// 3) the whole file content buffer if the above is not enough.
-  virtual bool canParse(file_magic magic, StringRef fileExtension,
-                        const MemoryBuffer &mb) const = 0;
-
-  /// \brief Parse a supplied buffer (already filled with the contents of a
-  /// file) and create a File object.
-  /// The resulting File object takes ownership of the MemoryBuffer.
-  virtual std::error_code
-  loadFile(std::unique_ptr<MemoryBuffer> mb, const class Registry &,
-           std::vector<std::unique_ptr<File>> &result) const = 0;
-};
-
-
-/// \brief An abstract class for handling alternate yaml representations
-/// of object files.
-///
-/// The YAML syntax allows "tags" which are used to specify the type of
-/// the YAML node.  In lld, top level YAML documents can be in many YAML
-/// representations (e.g mach-o encoded as yaml, etc).  A tag is used to
-/// specify which representation is used in the following YAML document.
-/// To work, there must be a YamlIOTaggedDocumentHandler registered that
-/// handles each tag type.
-class YamlIOTaggedDocumentHandler {
-public:
-  virtual ~YamlIOTaggedDocumentHandler();
-
-  /// This method is called on each registered YamlIOTaggedDocumentHandler
-  /// until one returns true.  If the subclass handles tag type !xyz, then
-  /// this method should call io.mapTag("!xzy") to see if that is the current
-  /// document type, and if so, process the rest of the document using
-  /// YAML I/O, then convert the result into an lld::File* and return it.
-  virtual bool handledDocTag(llvm::yaml::IO &io, const lld::File *&f) const = 0;
-};
-
-
-/// A registry to hold the list of currently registered Readers and
-/// tables which map Reference kind values to strings.
-/// The linker does not directly invoke Readers.  Instead, it registers
-/// Readers based on it configuration and command line options, then calls
-/// the Registry object to parse files.
-class Registry {
-public:
-  Registry();
-
-  /// Walk the list of registered Readers and find one that can parse the
-  /// supplied file and parse it.
-  std::error_code loadFile(std::unique_ptr<MemoryBuffer> mb,
-                           std::vector<std::unique_ptr<File>> &result) const;
-
-  /// Walk the list of registered kind tables to convert a Reference Kind
-  /// name to a value.
-  bool referenceKindFromString(StringRef inputStr, Reference::KindNamespace &ns,
-                               Reference::KindArch &a,
-                               Reference::KindValue &value) const;
-
-  /// Walk the list of registered kind tables to convert a Reference Kind
-  /// value to a string.
-  bool referenceKindToString(Reference::KindNamespace ns, Reference::KindArch a,
-                             Reference::KindValue value, StringRef &) const;
-
-  /// Walk the list of registered tag handlers and have the one that handles
-  /// the current document type process the yaml into an lld::File*.
-  bool handleTaggedDoc(llvm::yaml::IO &io, const lld::File *&file) const;
-
-  // These methods are called to dynamically add support for various file
-  // formats. The methods are also implemented in the appropriate lib*.a
-  // library, so that the code for handling a format is only linked in, if this
-  // method is used.  Any options that a Reader might need must be passed
-  // as parameters to the addSupport*() method.
-  void addSupportArchives(bool logLoading);
-  void addSupportYamlFiles();
-  void addSupportNativeObjects();
-  void addSupportCOFFObjects(PECOFFLinkingContext &);
-  void addSupportCOFFImportLibraries(PECOFFLinkingContext &);
-  void addSupportMachOObjects(MachOLinkingContext &);
-  void addSupportELFObjects(bool atomizeStrings, TargetHandlerBase *handler);
-  void addSupportELFDynamicSharedObjects(bool useShlibUndefines,
-                                         TargetHandlerBase *handler);
-
-  /// To convert between kind values and names, the registry walks the list
-  /// of registered kind tables. Each table is a zero terminated array of
-  /// KindStrings elements.
-  struct KindStrings {
-    Reference::KindValue  value;
-    StringRef             name;
-  };
-
-  /// A Reference Kind value is a tuple of <namespace, arch, value>.  All
-  /// entries in a conversion table have the same <namespace, arch>.  The
-  /// array then contains the value/name pairs.
-  void addKindTable(Reference::KindNamespace ns, Reference::KindArch arch,
-                    const KindStrings array[]);
-
-
-private:
-  struct KindEntry {
-    Reference::KindNamespace  ns;
-    Reference::KindArch       arch;
-    const KindStrings        *array;
-  };
-
-  void add(std::unique_ptr<Reader>);
-  void add(std::unique_ptr<YamlIOTaggedDocumentHandler>);
-
-  std::vector<std::unique_ptr<Reader>>                       _readers;
-  std::vector<std::unique_ptr<YamlIOTaggedDocumentHandler>>  _yamlHandlers;
-  std::vector<KindEntry>                                     _kindEntries;
-};
-
-// Utilities for building a KindString table.  For instance:
-//   static const Registry::KindStrings table[] = {
-//      LLD_KIND_STRING_ENTRY(R_VAX_ADDR16),
-//      LLD_KIND_STRING_ENTRY(R_VAX_DATA16),
-//      LLD_KIND_STRING_END
-//   };
-#define LLD_KIND_STRING_ENTRY(name) { name, #name }
-#define LLD_KIND_STRING_END         { 0,    "" }
-
-} // end namespace lld
-
-#endif
Index: include/lld/ReaderWriter/Writer.h
===================================================================
--- include/lld/ReaderWriter/Writer.h
+++ /dev/null
@@ -1,52 +0,0 @@
-//===- lld/ReaderWriter/Writer.h - Abstract File Format Interface ---------===//
-//
-//                             The LLVM Linker
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef LLD_READER_WRITER_WRITER_H
-#define LLD_READER_WRITER_WRITER_H
-
-#include "lld/Core/LLVM.h"
-#include <memory>
-#include <vector>
-
-namespace lld {
-class File;
-class ELFLinkingContext;
-class MachOLinkingContext;
-class PECOFFLinkingContext;
-class LinkingContext;
-class TargetHandlerBase;
-
-/// \brief The Writer is an abstract class for writing object files, shared
-/// library files, and executable files.  Each file format (e.g. ELF, mach-o,
-/// PECOFF, native, etc) have a concrete subclass of Writer.
-class Writer {
-public:
-  virtual ~Writer();
-
-  /// \brief Write a file from the supplied File object
-  virtual std::error_code writeFile(const File &linkedFile, StringRef path) = 0;
-
-  /// \brief This method is called by Core Linking to give the Writer a chance
-  /// to add file format specific "files" to set of files to be linked. This is
-  /// how file format specific atoms can be added to the link.
-  virtual bool createImplicitFiles(std::vector<std::unique_ptr<File> > &);
-
-protected:
-  // only concrete subclasses can be instantiated
-  Writer();
-};
-
-std::unique_ptr<Writer> createWriterELF(TargetHandlerBase *handler);
-std::unique_ptr<Writer> createWriterMachO(const MachOLinkingContext &);
-std::unique_ptr<Writer> createWriterPECOFF(const PECOFFLinkingContext &);
-std::unique_ptr<Writer> createWriterNative(const LinkingContext &);
-std::unique_ptr<Writer> createWriterYAML(const LinkingContext &);
-} // end namespace lld
-
-#endif
Index: lib/Core/CMakeLists.txt
===================================================================
--- lib/Core/CMakeLists.txt
+++ lib/Core/CMakeLists.txt
@@ -3,8 +3,10 @@
   Error.cpp
   File.cpp
   LinkingContext.cpp
+  Reader.cpp
   Resolver.cpp
   SymbolTable.cpp
+  Writer.cpp
   LINK_LIBS
     LLVMSupport
   )
Index: lib/Core/LinkingContext.cpp
===================================================================
--- lib/Core/LinkingContext.cpp
+++ lib/Core/LinkingContext.cpp
@@ -11,7 +11,7 @@
 #include "lld/Core/LinkingContext.h"
 #include "lld/Core/Resolver.h"
 #include "lld/Core/Simple.h"
-#include "lld/ReaderWriter/Writer.h"
+#include "lld/Core/Writer.h"
 #include "llvm/ADT/Triple.h"
 #include "llvm/Support/Process.h"
 
Index: lib/Core/Reader.cpp
===================================================================
--- /dev/null
+++ lib/Core/Reader.cpp
@@ -0,0 +1,119 @@
+//===- lib/Core/Reader.cpp ------------------------------------------------===//
+//
+//                             The LLVM Linker
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "lld/Core/File.h"
+#include "lld/Core/Reader.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/Errc.h"
+#include "llvm/Support/FileUtilities.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/Path.h"
+#include <memory>
+#include <system_error>
+
+namespace lld {
+
+YamlIOTaggedDocumentHandler::~YamlIOTaggedDocumentHandler() {}
+
+void Registry::add(std::unique_ptr<Reader> reader) {
+  _readers.push_back(std::move(reader));
+}
+
+void Registry::add(std::unique_ptr<YamlIOTaggedDocumentHandler> handler) {
+  _yamlHandlers.push_back(std::move(handler));
+}
+
+std::error_code
+Registry::loadFile(std::unique_ptr<MemoryBuffer> mb,
+                   std::vector<std::unique_ptr<File>> &result) const {
+  // Get file type.
+  StringRef content(mb->getBufferStart(), mb->getBufferSize());
+  llvm::sys::fs::file_magic fileType = llvm::sys::fs::identify_magic(content);
+  // Get file extension.
+  StringRef extension = llvm::sys::path::extension(mb->getBufferIdentifier());
+
+  // Ask each registered reader if it can handle this file type or extension.
+  for (const std::unique_ptr<Reader> &reader : _readers) {
+    if (!reader->canParse(fileType, extension, *mb))
+      continue;
+    if (std::error_code ec = reader->loadFile(std::move(mb), *this, result))
+      return ec;
+    return std::error_code();
+  }
+
+  // No Reader could parse this file.
+  return make_error_code(llvm::errc::executable_format_error);
+}
+
+static const Registry::KindStrings kindStrings[] = {
+    {Reference::kindInGroup, "in-group"},
+    {Reference::kindLayoutAfter, "layout-after"},
+    {Reference::kindLayoutBefore, "layout-before"},
+    {Reference::kindGroupChild, "group-child"},
+    {Reference::kindAssociate, "associate"},
+    LLD_KIND_STRING_END};
+
+Registry::Registry() {
+  addKindTable(Reference::KindNamespace::all, Reference::KindArch::all,
+               kindStrings);
+}
+
+bool Registry::handleTaggedDoc(llvm::yaml::IO &io,
+                               const lld::File *&file) const {
+  for (const std::unique_ptr<YamlIOTaggedDocumentHandler> &h : _yamlHandlers)
+    if (h->handledDocTag(io, file))
+      return true;
+  return false;
+}
+
+
+void Registry::addKindTable(Reference::KindNamespace ns,
+                            Reference::KindArch arch,
+                            const KindStrings array[]) {
+  KindEntry entry = { ns, arch, array };
+  _kindEntries.push_back(entry);
+}
+
+bool Registry::referenceKindFromString(StringRef inputStr,
+                                       Reference::KindNamespace &ns,
+                                       Reference::KindArch &arch,
+                                       Reference::KindValue &value) const {
+  for (const KindEntry &entry : _kindEntries) {
+    for (const KindStrings *pair = entry.array; !pair->name.empty(); ++pair) {
+      if (!inputStr.equals(pair->name))
+        continue;
+      ns = entry.ns;
+      arch = entry.arch;
+      value = pair->value;
+      return true;
+    }
+  }
+  return false;
+}
+
+bool Registry::referenceKindToString(Reference::KindNamespace ns,
+                                     Reference::KindArch arch,
+                                     Reference::KindValue value,
+                                     StringRef &str) const {
+  for (const KindEntry &entry : _kindEntries) {
+    if (entry.ns != ns)
+      continue;
+    if (entry.arch != arch)
+      continue;
+    for (const KindStrings *pair = entry.array; !pair->name.empty(); ++pair) {
+      if (pair->value != value)
+        continue;
+      str = pair->name;
+      return true;
+    }
+  }
+  return false;
+}
+
+} // end namespace lld
Index: lib/Core/Writer.cpp
===================================================================
--- /dev/null
+++ lib/Core/Writer.cpp
@@ -0,0 +1,23 @@
+//===- lib/Core/Writer.cpp ------------------------------------------------===//
+//
+//                             The LLVM Linker
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "lld/Core/File.h"
+#include "lld/Core/Writer.h"
+
+namespace lld {
+Writer::Writer() {
+}
+
+Writer::~Writer() {
+}
+
+bool Writer::createImplicitFiles(std::vector<std::unique_ptr<File> > &) {
+  return true;
+}
+} // end namespace lld
Index: lib/Driver/CoreDriver.cpp
===================================================================
--- lib/Driver/CoreDriver.cpp
+++ lib/Driver/CoreDriver.cpp
@@ -7,9 +7,9 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "lld/Core/Reader.h"
 #include "lld/Driver/Driver.h"
 #include "lld/ReaderWriter/CoreLinkingContext.h"
-#include "lld/ReaderWriter/Reader.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/Triple.h"
Index: lib/Driver/Driver.cpp
===================================================================
--- lib/Driver/Driver.cpp
+++ lib/Driver/Driver.cpp
@@ -13,12 +13,12 @@
 #include "lld/Core/LLVM.h"
 #include "lld/Core/Parallel.h"
 #include "lld/Core/PassManager.h"
+#include "lld/Core/Reader.h"
 #include "lld/Core/Resolver.h"
+#include "lld/Core/Writer.h"
 #include "lld/Driver/Driver.h"
 #include "lld/Passes/RoundTripNativePass.h"
 #include "lld/Passes/RoundTripYAMLPass.h"
-#include "lld/ReaderWriter/Reader.h"
-#include "lld/ReaderWriter/Writer.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/Option/Arg.h"
Index: lib/Passes/CMakeLists.txt
===================================================================
--- lib/Passes/CMakeLists.txt
+++ lib/Passes/CMakeLists.txt
@@ -3,6 +3,8 @@
   RoundTripNativePass.cpp
   RoundTripYAMLPass.cpp
   LINK_LIBS
-    lldReaderWriter
+    lldCore
+    lldNative
+    lldYAML
     LLVMSupport
   )
Index: lib/Passes/RoundTripNativePass.cpp
===================================================================
--- lib/Passes/RoundTripNativePass.cpp
+++ lib/Passes/RoundTripNativePass.cpp
@@ -9,8 +9,8 @@
 
 #include "lld/Core/Instrumentation.h"
 #include "lld/Core/Simple.h"
+#include "lld/Core/Writer.h"
 #include "lld/Passes/RoundTripNativePass.h"
-#include "lld/ReaderWriter/Writer.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/Path.h"
 #include <memory>
Index: lib/Passes/RoundTripYAMLPass.cpp
===================================================================
--- lib/Passes/RoundTripYAMLPass.cpp
+++ lib/Passes/RoundTripYAMLPass.cpp
@@ -9,8 +9,8 @@
 
 #include "lld/Core/Instrumentation.h"
 #include "lld/Core/Simple.h"
+#include "lld/Core/Writer.h"
 #include "lld/Passes/RoundTripYAMLPass.h"
-#include "lld/ReaderWriter/Writer.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/Path.h"
 #include <memory>
Index: lib/ReaderWriter/CMakeLists.txt
===================================================================
--- lib/ReaderWriter/CMakeLists.txt
+++ lib/ReaderWriter/CMakeLists.txt
@@ -12,11 +12,10 @@
   CoreLinkingContext.cpp
   FileArchive.cpp
   LinkerScript.cpp
-  Reader.cpp
-  Writer.cpp
-  FileArchive.cpp
   LINK_LIBS
     lldCore
+    lldPasses
+    lldYAML
     LLVMObject
     LLVMSupport
   )
Index: lib/ReaderWriter/ELF/ELFReader.h
===================================================================
--- lib/ReaderWriter/ELF/ELFReader.h
+++ lib/ReaderWriter/ELF/ELFReader.h
@@ -13,7 +13,7 @@
 #include "CreateELF.h"
 #include "DynamicFile.h"
 #include "ELFFile.h"
-#include "lld/ReaderWriter/Reader.h"
+#include "lld/Core/Reader.h"
 
 namespace lld {
 namespace elf {
Index: lib/ReaderWriter/ELF/OutputELFWriter.h
===================================================================
--- lib/ReaderWriter/ELF/OutputELFWriter.h
+++ lib/ReaderWriter/ELF/OutputELFWriter.h
@@ -16,7 +16,7 @@
 #include "lld/Core/Parallel.h"
 #include "lld/Core/SharedLibraryFile.h"
 #include "lld/ReaderWriter/ELFLinkingContext.h"
-#include "lld/ReaderWriter/Writer.h"
+#include "lld/Core/Writer.h"
 #include "llvm/ADT/StringSet.h"
 #include "llvm/Support/Path.h"
 
Index: lib/ReaderWriter/ELF/SegmentChunks.h
===================================================================
--- lib/ReaderWriter/ELF/SegmentChunks.h
+++ lib/ReaderWriter/ELF/SegmentChunks.h
@@ -15,7 +15,7 @@
 #include "SectionChunks.h"
 #include "Writer.h"
 #include "lld/Core/range.h"
-#include "lld/ReaderWriter/Writer.h"
+#include "lld/Core/Writer.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Object/ELF.h"
Index: lib/ReaderWriter/ELF/Writer.h
===================================================================
--- lib/ReaderWriter/ELF/Writer.h
+++ lib/ReaderWriter/ELF/Writer.h
@@ -11,7 +11,7 @@
 #define LLD_READER_WRITER_ELF_WRITER_H
 
 #include "lld/Core/File.h"
-#include "lld/ReaderWriter/Writer.h"
+#include "lld/Core/Writer.h"
 
 namespace lld {
 namespace elf {
Index: lib/ReaderWriter/ELF/Writer.cpp
===================================================================
--- lib/ReaderWriter/ELF/Writer.cpp
+++ lib/ReaderWriter/ELF/Writer.cpp
@@ -7,7 +7,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "lld/ReaderWriter/Writer.h"
+#include "lld/Core/Writer.h"
 #include "DynamicLibraryWriter.h"
 #include "ExecutableWriter.h"
 
Index: lib/ReaderWriter/MachO/MachOLinkingContext.cpp
===================================================================
--- lib/ReaderWriter/MachO/MachOLinkingContext.cpp
+++ lib/ReaderWriter/MachO/MachOLinkingContext.cpp
@@ -14,11 +14,11 @@
 #include "MachOPasses.h"
 #include "lld/Core/ArchiveLibraryFile.h"
 #include "lld/Core/PassManager.h"
+#include "lld/Core/Reader.h"
+#include "lld/Core/Writer.h"
 #include "lld/Driver/Driver.h"
 #include "lld/Passes/LayoutPass.h"
 #include "lld/Passes/RoundTripYAMLPass.h"
-#include "lld/ReaderWriter/Reader.h"
-#include "lld/ReaderWriter/Writer.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/Triple.h"
 #include "llvm/Config/config.h"
Index: lib/ReaderWriter/MachO/WriterMachO.cpp
===================================================================
--- lib/ReaderWriter/MachO/WriterMachO.cpp
+++ lib/ReaderWriter/MachO/WriterMachO.cpp
@@ -7,10 +7,10 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "lld/ReaderWriter/Writer.h"
 #include "ExecutableAtoms.hpp"
 #include "MachONormalizedFile.h"
 #include "lld/Core/File.h"
+#include "lld/Core/Writer.h"
 #include "lld/ReaderWriter/MachOLinkingContext.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
Index: lib/ReaderWriter/Native/CMakeLists.txt
===================================================================
--- lib/ReaderWriter/Native/CMakeLists.txt
+++ lib/ReaderWriter/Native/CMakeLists.txt
@@ -2,6 +2,6 @@
   ReaderNative.cpp
   WriterNative.cpp
   LINK_LIBS
-    lldReaderWriter
+    lldCore
     LLVMSupport
   )
Index: lib/ReaderWriter/Native/Makefile
===================================================================
--- lib/ReaderWriter/Native/Makefile
+++ lib/ReaderWriter/Native/Makefile
@@ -9,6 +9,6 @@
 
 LLD_LEVEL := ../../..
 LIBRARYNAME := lldNative
-USEDLIBS = lldReaderWriter.a lldCore.a
+USEDLIBS = lldCore.a
 
 include $(LLD_LEVEL)/Makefile
Index: lib/ReaderWriter/Native/ReaderNative.cpp
===================================================================
--- lib/ReaderWriter/Native/ReaderNative.cpp
+++ lib/ReaderWriter/Native/ReaderNative.cpp
@@ -11,8 +11,8 @@
 #include "lld/Core/Atom.h"
 #include "lld/Core/Error.h"
 #include "lld/Core/File.h"
+#include "lld/Core/Reader.h"
 #include "lld/Core/Simple.h"
-#include "lld/ReaderWriter/Reader.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Debug.h"
Index: lib/ReaderWriter/Native/WriterNative.cpp
===================================================================
--- lib/ReaderWriter/Native/WriterNative.cpp
+++ lib/ReaderWriter/Native/WriterNative.cpp
@@ -7,10 +7,10 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "lld/ReaderWriter/Writer.h"
 #include "NativeFileFormat.h"
 #include "lld/Core/File.h"
 #include "lld/Core/LinkingContext.h"
+#include "lld/Core/Writer.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/StringRef.h"
Index: lib/ReaderWriter/PECOFF/PECOFFLinkingContext.cpp
===================================================================
--- lib/ReaderWriter/PECOFF/PECOFFLinkingContext.cpp
+++ lib/ReaderWriter/PECOFF/PECOFFLinkingContext.cpp
@@ -16,13 +16,13 @@
 #include "LoadConfigPass.h"
 #include "PDBPass.h"
 #include "lld/Core/PassManager.h"
+#include "lld/Core/Reader.h"
 #include "lld/Core/Simple.h"
+#include "lld/Core/Writer.h"
 #include "lld/Passes/LayoutPass.h"
 #include "lld/Passes/RoundTripNativePass.h"
 #include "lld/Passes/RoundTripYAMLPass.h"
 #include "lld/ReaderWriter/PECOFFLinkingContext.h"
-#include "lld/ReaderWriter/Reader.h"
-#include "lld/ReaderWriter/Writer.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/Support/Allocator.h"
 #include "llvm/Support/Path.h"
Index: lib/ReaderWriter/PECOFF/ReaderCOFF.cpp
===================================================================
--- lib/ReaderWriter/PECOFF/ReaderCOFF.cpp
+++ lib/ReaderWriter/PECOFF/ReaderCOFF.cpp
@@ -10,9 +10,9 @@
 #include "Atoms.h"
 #include "lld/Core/Alias.h"
 #include "lld/Core/File.h"
+#include "lld/Core/Reader.h"
 #include "lld/Driver/Driver.h"
 #include "lld/ReaderWriter/PECOFFLinkingContext.h"
-#include "lld/ReaderWriter/Reader.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Object/COFF.h"
Index: lib/ReaderWriter/PECOFF/WriterPECOFF.cpp
===================================================================
--- lib/ReaderWriter/PECOFF/WriterPECOFF.cpp
+++ lib/ReaderWriter/PECOFF/WriterPECOFF.cpp
@@ -23,9 +23,9 @@
 #include "WriterImportLibrary.h"
 #include "lld/Core/DefinedAtom.h"
 #include "lld/Core/File.h"
+#include "lld/Core/Writer.h"
 #include "lld/ReaderWriter/AtomLayout.h"
 #include "lld/ReaderWriter/PECOFFLinkingContext.h"
-#include "lld/ReaderWriter/Writer.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/Object/COFF.h"
 #include "llvm/Support/COFF.h"
Index: lib/ReaderWriter/Reader.cpp
===================================================================
--- lib/ReaderWriter/Reader.cpp
+++ /dev/null
@@ -1,119 +0,0 @@
-//===- lib/ReaderWriter/Reader.cpp ----------------------------------------===//
-//
-//                             The LLVM Linker
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-#include "lld/Core/File.h"
-#include "lld/ReaderWriter/Reader.h"
-#include "llvm/ADT/StringRef.h"
-#include "llvm/Support/Errc.h"
-#include "llvm/Support/FileUtilities.h"
-#include "llvm/Support/MemoryBuffer.h"
-#include "llvm/Support/Path.h"
-#include <memory>
-#include <system_error>
-
-namespace lld {
-
-YamlIOTaggedDocumentHandler::~YamlIOTaggedDocumentHandler() {}
-
-void Registry::add(std::unique_ptr<Reader> reader) {
-  _readers.push_back(std::move(reader));
-}
-
-void Registry::add(std::unique_ptr<YamlIOTaggedDocumentHandler> handler) {
-  _yamlHandlers.push_back(std::move(handler));
-}
-
-std::error_code
-Registry::loadFile(std::unique_ptr<MemoryBuffer> mb,
-                   std::vector<std::unique_ptr<File>> &result) const {
-  // Get file type.
-  StringRef content(mb->getBufferStart(), mb->getBufferSize());
-  llvm::sys::fs::file_magic fileType = llvm::sys::fs::identify_magic(content);
-  // Get file extension.
-  StringRef extension = llvm::sys::path::extension(mb->getBufferIdentifier());
-
-  // Ask each registered reader if it can handle this file type or extension.
-  for (const std::unique_ptr<Reader> &reader : _readers) {
-    if (!reader->canParse(fileType, extension, *mb))
-      continue;
-    if (std::error_code ec = reader->loadFile(std::move(mb), *this, result))
-      return ec;
-    return std::error_code();
-  }
-
-  // No Reader could parse this file.
-  return make_error_code(llvm::errc::executable_format_error);
-}
-
-static const Registry::KindStrings kindStrings[] = {
-    {Reference::kindInGroup, "in-group"},
-    {Reference::kindLayoutAfter, "layout-after"},
-    {Reference::kindLayoutBefore, "layout-before"},
-    {Reference::kindGroupChild, "group-child"},
-    {Reference::kindAssociate, "associate"},
-    LLD_KIND_STRING_END};
-
-Registry::Registry() {
-  addKindTable(Reference::KindNamespace::all, Reference::KindArch::all,
-               kindStrings);
-}
-
-bool Registry::handleTaggedDoc(llvm::yaml::IO &io,
-                               const lld::File *&file) const {
-  for (const std::unique_ptr<YamlIOTaggedDocumentHandler> &h : _yamlHandlers)
-    if (h->handledDocTag(io, file))
-      return true;
-  return false;
-}
-
-
-void Registry::addKindTable(Reference::KindNamespace ns,
-                            Reference::KindArch arch,
-                            const KindStrings array[]) {
-  KindEntry entry = { ns, arch, array };
-  _kindEntries.push_back(entry);
-}
-
-bool Registry::referenceKindFromString(StringRef inputStr,
-                                       Reference::KindNamespace &ns,
-                                       Reference::KindArch &arch,
-                                       Reference::KindValue &value) const {
-  for (const KindEntry &entry : _kindEntries) {
-    for (const KindStrings *pair = entry.array; !pair->name.empty(); ++pair) {
-      if (!inputStr.equals(pair->name))
-        continue;
-      ns = entry.ns;
-      arch = entry.arch;
-      value = pair->value;
-      return true;
-    }
-  }
-  return false;
-}
-
-bool Registry::referenceKindToString(Reference::KindNamespace ns,
-                                     Reference::KindArch arch,
-                                     Reference::KindValue value,
-                                     StringRef &str) const {
-  for (const KindEntry &entry : _kindEntries) {
-    if (entry.ns != ns)
-      continue;
-    if (entry.arch != arch)
-      continue;
-    for (const KindStrings *pair = entry.array; !pair->name.empty(); ++pair) {
-      if (pair->value != value)
-        continue;
-      str = pair->name;
-      return true;
-    }
-  }
-  return false;
-}
-
-} // end namespace lld
Index: lib/ReaderWriter/Writer.cpp
===================================================================
--- lib/ReaderWriter/Writer.cpp
+++ /dev/null
@@ -1,23 +0,0 @@
-//===- lib/ReaderWriter/Writer.cpp ----------------------------------------===//
-//
-//                             The LLVM Linker
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-#include "lld/Core/File.h"
-#include "lld/ReaderWriter/Writer.h"
-
-namespace lld {
-Writer::Writer() {
-}
-
-Writer::~Writer() {
-}
-
-bool Writer::createImplicitFiles(std::vector<std::unique_ptr<File> > &) {
-  return true;
-}
-} // end namespace lld
Index: lib/ReaderWriter/YAML/CMakeLists.txt
===================================================================
--- lib/ReaderWriter/YAML/CMakeLists.txt
+++ lib/ReaderWriter/YAML/CMakeLists.txt
@@ -1,6 +1,6 @@
 add_llvm_library(lldYAML
   ReaderWriterYAML.cpp
   LINK_LIBS
-    lldReaderWriter
+    lldCore
     LLVMSupport
   )
Index: lib/ReaderWriter/YAML/Makefile
===================================================================
--- lib/ReaderWriter/YAML/Makefile
+++ lib/ReaderWriter/YAML/Makefile
@@ -9,6 +9,6 @@
 
 LLD_LEVEL := ../../..
 LIBRARYNAME := lldYAML
-USEDLIBS = lldReaderWriter.a lldCore.a
+USEDLIBS = lldCore.a
 
 include $(LLD_LEVEL)/Makefile
Index: lib/ReaderWriter/YAML/ReaderWriterYAML.cpp
===================================================================
--- lib/ReaderWriter/YAML/ReaderWriterYAML.cpp
+++ lib/ReaderWriter/YAML/ReaderWriterYAML.cpp
@@ -12,10 +12,10 @@
 #include "lld/Core/Error.h"
 #include "lld/Core/File.h"
 #include "lld/Core/LLVM.h"
+#include "lld/Core/Reader.h"
 #include "lld/Core/Reference.h"
 #include "lld/Core/Simple.h"
-#include "lld/ReaderWriter/Reader.h"
-#include "lld/ReaderWriter/Writer.h"
+#include "lld/Core/Writer.h"
 #include "lld/ReaderWriter/YamlContext.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/StringMap.h"