--- /dev/null
+++ dyld/dyld-1162/cache_builder/BuilderFileSystem.h
@@ -0,0 +1,110 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
+*
+* Copyright (c) 2017 Apple Inc. All rights reserved.
+*
+* @APPLE_LICENSE_HEADER_START@
+*
+* This file contains Original Code and/or Modifications of Original Code
+* as defined in and that are subject to the Apple Public Source License
+* Version 2.0 (the 'License'). You may not use this file except in
+* compliance with the License. Please obtain a copy of the License at
+* http://www.opensource.apple.com/apsl/ and read it before using this
+* file.
+*
+* The Original Code and all software distributed under the License are
+* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+* Please see the License for the specific language governing rights and
+* limitations under the License.
+*
+* @APPLE_LICENSE_HEADER_END@
+*/
+
+#ifndef BuilderFileSystem_hpp
+#define BuilderFileSystem_hpp
+
+#include "ClosureFileSystem.h"
+#include "mrm_shared_cache_builder.h"
+#include "Diagnostics.h"
+#include "FileUtils.h"
+
+#include <map>
+#include <string>
+#include <vector>
+
+namespace cache_builder
+{
+
+class SymlinkResolver {
+public:
+    SymlinkResolver() { }
+
+    void addFile(Diagnostics& diags, std::string path);
+
+    void addSymlink(Diagnostics& diags, std::string fromPath, std::string toPath);
+
+    std::string realPath(Diagnostics& diags, const std::string& path,
+                         void (^callback)(const std::string& intermediateSymlink) = nullptr) const;
+
+    std::vector<cache_builder::FileAlias> getResolvedSymlinks(void (^callback)(const std::string& error)) const;
+
+    std::vector<cache_builder::FileAlias> getIntermediateSymlinks() const;
+
+private:
+    std::set<std::string> filePaths;
+    std::map<std::string, std::string> symlinks;
+};
+
+struct FileInfo {
+    std::string     path;
+    const uint8_t*  data;
+    const uint64_t  length;
+    FileFlags       flags;
+    uint64_t        mtime;
+    uint64_t        inode;
+};
+
+class FileSystemMRM : public dyld3::closure::FileSystem
+{
+public:
+    FileSystemMRM() : FileSystem() { }
+
+    bool getRealPath(const char possiblePath[MAXPATHLEN], char realPath[MAXPATHLEN]) const override;
+
+    bool loadFile(const char* path, dyld3::closure::LoadedFileInfo& info,
+                  char realerPath[MAXPATHLEN], void (^error)(const char* format, ...)) const override;
+
+    void unloadFile(const dyld3::closure::LoadedFileInfo& info) const override;
+
+    void unloadPartialFile(dyld3::closure::LoadedFileInfo& info,
+                           uint64_t keepStartOffset, uint64_t keepLength) const override;
+
+    bool fileExists(const char* path, uint64_t* inode=nullptr, uint64_t* mtime=nullptr,
+                    bool* issetuid=nullptr, bool* inodesMatchRuntime = nullptr) const override;
+
+    // MRM file APIs
+    bool addFile(const char* path, uint8_t* data, uint64_t size, Diagnostics& diag, FileFlags fileFlags,
+                 uint64_t inode, uint64_t modTime);
+
+    bool addSymlink(const char* fromPath, const char* toPath, Diagnostics& diag);
+
+    void forEachFileInfo(std::function<void(const char* path, const void* buffer, size_t bufferSize,
+                                            FileFlags fileFlags, uint64_t inode, uint64_t modTime)> lambda);
+
+    size_t fileCount() const;
+
+    std::vector<cache_builder::FileAlias> getResolvedSymlinks(void (^callback)(const std::string& error)) const;
+
+    std::vector<cache_builder::FileAlias> getIntermediateSymlinks() const;
+
+private:
+    std::vector<FileInfo> files;
+    std::map<std::string, uint64_t> fileMap;
+    SymlinkResolver symlinkResolver;
+};
+
+} // namespace cache_builder
+
+#endif /* BuilderFileSystem_hpp */