--- /dev/null
+++ dyld/dyld-1330/framework/AtlasCache.swift
@@ -0,0 +1,136 @@
+/* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*- vim: ft=cpp et ts=4 sw=4:
+ *
+ * Copyright (c) 2023 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@
+ */
+
+import os
+import System
+@_implementationOnly import Dyld_Internal
+
+@available(macOS 13.0, *)
+struct AtlasCache {
+    var uuidMap = [UUID : BPList.UnsafeRawDictionary]()
+    var pathMap = [String : BPList.UnsafeRawDictionary]()
+    var buffers = [Data]()
+    let lock = OSAllocatedUnfairLock()
+    mutating func getCachePlist(uuid: UUID?, path: FilePath?, forceScavenge: Bool) -> BPList.UnsafeRawDictionary? {
+        return try? lock.withLockUnchecked { () -> BPList.UnsafeRawDictionary? in
+            //FIXME: Delegate support
+            if let uuid, let result = uuidMap[uuid] {
+                return result
+            }
+            guard let path else {
+                return nil
+            }
+            if !forceScavenge, let result = pathMap[path.string] {
+                return result
+            }
+            guard let atlasFileName = path.lastComponent?.stem.appending(".atlas") else {
+                return  nil
+            }
+            var embeddedData = try? Data(contentsOf:URL(fileURLWithPath:path.removingLastComponent().appending(atlasFileName).string), options:.mappedIfSafe)
+            var scavengedData: Data? = nil
+            if forceScavenge || embeddedData == nil {
+                embeddedData = nil
+                var scavengedBufferSize = UInt64(0)
+                if let scavegedBuffer =  scavengeCache(path.string, &scavengedBufferSize) {
+                    scavengedData = Data(bytesNoCopy:scavegedBuffer, count:Int(scavengedBufferSize), deallocator:.free)
+                }
+            }
+            let data = embeddedData ?? scavengedData
+            guard let data else { return nil }
+            buffers.append(data)
+            var archive  = try AARDecoder(data:data)
+            let archivePath = uuid?.cacheAtlasArchivePath ?? "caches/names/\(path.lastComponent!.string).plist"
+            guard let plistData = try? archive.data(path: archivePath),
+                  let atlasesDict = try? BPList(data:plistData).asDictionary(),
+                  let byNameDict = try atlasesDict[.string("names")]?.asDictionary(),
+                  let byUuidDict = try atlasesDict[.string("uuids")]?.asDictionary() else {
+                return nil
+            }
+            var skipValidation = false
+            if scavengedData == nil {
+                for prefix in SharedCache.sharedCachePaths {
+                    if path.string.hasPrefix(prefix) {
+                        // The shared cache is coming from snapshot protected storage, skip validation
+                        skipValidation = true
+                        break
+                    }
+                }
+            }
+            if !skipValidation {
+                do {
+                    for (_,atlas) in byNameDict {
+                        guard let atlasDict = try? atlas.asDictionary() else {
+                            throw AtlasError.placeHolder
+                        }
+                        try SharedCache.Impl.validate(bplist:atlasDict)
+                    }
+                    for (_,atlas) in byUuidDict {
+                        guard let atlasDict = try? atlas.asDictionary() else {
+                            throw AtlasError.placeHolder
+                        }
+                        try SharedCache.Impl.validate(bplist:atlasDict)
+                    }
+                } catch {
+                    return nil
+                }
+            }
+            for (key,atlas) in byUuidDict {
+                guard let atlasUUID = UUID(uuidString: key.asString()) else {
+                    continue
+                }
+                if uuidMap[atlasUUID] == nil {
+                    uuidMap[atlasUUID] = try! atlas.asDictionary()
+                }
+            }
+            let dirname = path.removingLastComponent()
+            for (atlasName,atlas) in byNameDict {
+                let fullPath = dirname.appending(atlasName.asString()).string
+                let atlasDict = try! atlas.asDictionary()
+                if pathMap[fullPath] == nil {
+                    pathMap[fullPath] = atlasDict
+                }
+            }
+            if let uuid {
+                return uuidMap[uuid]
+            }
+            return pathMap[path.string]
+        }
+    }
+}
+
+@available(macOS 13.0, *)
+fileprivate var bufferCache = AtlasCache()
+
+internal extension Snapshot {
+    static func findCacheBPlist(uuid: UUID?, path: FilePath?, forceScavenge: Bool = false) -> BPList.UnsafeRawDictionary? {
+        if #available(macOS 13.0, *) {
+            guard let plist = bufferCache.getCachePlist(uuid:uuid, path:path, forceScavenge:forceScavenge) else {
+                return nil
+            }
+            return plist
+        } else {
+            fatalError("This is not supported for backdeployment, but needs to build with a reduced minOS in some environments")
+        }
+    }
+}