--- a/config/external/moz.build
+++ b/config/external/moz.build
@@ -8,27 +8,23 @@ external_dirs = []
 
 DIRS += [
     'lgpllibs',
     'sqlite',
 ]
 if not CONFIG['MOZ_SYSTEM_JPEG']:
     external_dirs += ['media/libjpeg']
 
-if CONFIG['MOZ_UPDATER']:
-    if CONFIG['MOZ_WIDGET_TOOLKIT'] != 'android'
-        external_dirs += ['modules/libbz2']
+if CONFIG['MOZ_WIDGET_TOOLKIT'] != 'android':
+    external_dirs += ['modules/xz']
 
 # There's no "native" brotli or woff2 yet, but probably in the future...
 external_dirs += ['modules/brotli']
 external_dirs += ['modules/woff2']
 
-if CONFIG['MOZ_WIDGET_TOOLKIT'] != 'android':
-    external_dirs += ['modules/xz']
-
 if CONFIG['MOZ_VORBIS']:
     external_dirs += ['media/libvorbis']
 
 if CONFIG['MOZ_TREMOR']:
     external_dirs += ['media/libtremor']
 
 if CONFIG['MOZ_WEBM_ENCODER']:
     external_dirs += ['media/libmkv']

--- a/toolkit/mozapps/update/common/errors.h
+++ b/toolkit/mozapps/update/common/errors.h
@@ -52,21 +52,24 @@
 #define SERVICE_UPDATER_NOT_FIXED_DRIVE 31
 #define SERVICE_COULD_NOT_LOCK_UPDATER 32
 #define SERVICE_INSTALLDIR_ERROR 33
 
 #define NO_INSTALLDIR_ERROR 34
 #define WRITE_ERROR_ACCESS_DENIED 35
 // #define WRITE_ERROR_SHARING_VIOLATION 36 // Replaced with errors 46-48
 #define WRITE_ERROR_CALLBACK_APP 37
-#define UNEXPECTED_BZIP_ERROR 39
-#define UNEXPECTED_MAR_ERROR 40
+// UNEXPECTED_BZIP_ERROR and UNEXPECTED_MAR_ERROR are never returned now
+// that LZMA is used instead of BZ2.
+// #define UNEXPECTED_BZIP_ERROR 39
+// #define UNEXPECTED_MAR_ERROR 40
 #define UNEXPECTED_BSPATCH_ERROR 41
 #define UNEXPECTED_FILE_OPERATION_ERROR 42
-// #define FILESYSTEM_MOUNT_READWRITE_ERROR 43 // Removed support for gonk
+// 43 was previously FILESYSTEM_MOUNT_READWRITE_ERROR, which was gonk-only
+#define UNEXPECTED_XZ_ERROR 43
 #define DELETE_ERROR_EXPECTED_DIR 46
 #define DELETE_ERROR_EXPECTED_FILE 47
 #define RENAME_ERROR_EXPECTED_FILE 48
 
 // Error codes 24-33 and 49-57 are for the Windows maintenance service.
 #define SERVICE_COULD_NOT_COPY_UPDATER 49
 #define SERVICE_STILL_APPLYING_TERMINATED 50
 #define SERVICE_STILL_APPLYING_NO_EXIT_CODE 51

--- a/toolkit/mozapps/update/updater/archivereader.cpp
+++ b/toolkit/mozapps/update/updater/archivereader.cpp
@@ -2,17 +2,16 @@
 /* vim:set ts=2 sw=2 sts=2 et cindent: */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include <string.h>
 #include <stdlib.h>
 #include <fcntl.h>
-#include "bzlib.h"
 #include "archivereader.h"
 #include "errors.h"
 #ifdef XP_WIN
 #include "nsAlgorithm.h" // Needed by nsVersionComparator.cpp
 #include "updatehelper.h"
 #endif
 
 // These are generated at compile time based on the DER file for the channel
@@ -266,59 +265,30 @@ ArchiveReader::ExtractFileToStream(const
     return READ_ERROR;
 
   return ExtractItemToStream(item, fp);
 }
 
 int
 ArchiveReader::ExtractItemToStream(const MarItem *item, FILE *fp)
 {
-  /* decompress the data chunk by chunk */
-
-  bz_stream strm;
-  int offset, inlen, outlen, ret = OK;
-
-  memset(&strm, 0, sizeof(strm));
-  if (BZ2_bzDecompressInit(&strm, 0, 0) != BZ_OK)
-    return UNEXPECTED_BZIP_ERROR;
-
-  offset = 0;
-  for (;;) {
-    if (!item->length) {
-      ret = UNEXPECTED_MAR_ERROR;
-      break;
-    }
+  // We shouldn't extract from the archive until after we know the signature is
+  // good, so that we don't run a bunch of complicated decompression code on
+  // a file of unknown validity. That means that, if signatures are being
+  // checked, the check should be done before this function is ever called.
+  if (mar_decompress(mArchive) == -1) {
+    return UNEXPECTED_XZ_ERROR;
+  }
 
-    if (offset < (int) item->length && strm.avail_in == 0) {
-      inlen = mar_read(mArchive, item, offset, inbuf, inbuf_size);
-      if (inlen <= 0)
-        return READ_ERROR;
-      offset += inlen;
-      strm.next_in = inbuf;
-      strm.avail_in = inlen;
+  int offset = 0;
+  while (offset < (int)(item->length)) {
+    int inlen = mar_read(mArchive, item, offset, inbuf, inbuf_size);
+    if (inlen <= 0) {
+      return READ_ERROR;
     }
-
-    strm.next_out = outbuf;
-    strm.avail_out = outbuf_size;
-
-    ret = BZ2_bzDecompress(&strm);
-    if (ret != BZ_OK && ret != BZ_STREAM_END) {
-      ret = UNEXPECTED_BZIP_ERROR;
-      break;
-    }
-
-    outlen = outbuf_size - strm.avail_out;
-    if (outlen) {
-      if (fwrite(outbuf, outlen, 1, fp) != 1) {
-        ret = WRITE_ERROR_EXTRACT;
-        break;
-      }
-    }
-
-    if (ret == BZ_STREAM_END) {
-      ret = OK;
-      break;
+    offset += inlen;
+    if (fwrite(inbuf, inlen, 1, fp) != 1) {
+      return WRITE_ERROR_EXTRACT;
     }
   }
 
-  BZ2_bzDecompressEnd(&strm);
-  return ret;
+  return OK;
 }

--- a/toolkit/mozapps/update/updater/archivereader.h
+++ b/toolkit/mozapps/update/updater/archivereader.h
@@ -6,19 +6,20 @@
 
 #ifndef ArchiveReader_h__
 #define ArchiveReader_h__
 
 #include <stdio.h>
 #include "mar.h"
 
 #ifdef XP_WIN
-  typedef WCHAR NS_tchar;
+#include <windows.h>
+typedef WCHAR NS_tchar;
 #else
-  typedef char NS_tchar;
+typedef char NS_tchar;
 #endif
 
 // This class provides an API to extract files from an update archive.
 class ArchiveReader
 {
 public:
   ArchiveReader() : mArchive(nullptr) {}
   ~ArchiveReader() { Close(); }

--- a/toolkit/mozapps/update/updater/updater-common.build
+++ b/toolkit/mozapps/update/updater/updater-common.build
@@ -55,17 +55,16 @@ else:
     USE_LIBS += [
         'updatecommon',
     ]
 
 USE_LIBS += [
     'lzma',
     'mar',
 ]
-
 DEFINES['LZMA_API_STATIC'] = 1
 HOST_DEFINES['LZMA_API_STATIC'] = 1
 
 if 'gtk' in CONFIG['MOZ_WIDGET_TOOLKIT']:
     have_progressui = 1
     srcs += [
         'progressui_gtk.cpp',
     ]

--- a/toolkit/mozapps/update/updater/updater.cpp
+++ b/toolkit/mozapps/update/updater/updater.cpp
@@ -33,17 +33,17 @@
  *  -----------
  *  method   = "remove" | "rmdir"
  */
 #include "bspatch.h"
 #include "progressui.h"
 #include "archivereader.h"
 #include "readstrings.h"
 #include "errors.h"
-#include "bzlib.h"
+#include "lzma.h"
 
 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
 #include <stdarg.h>
 
 #include <sys/types.h>
 #include <sys/stat.h>
@@ -135,47 +135,16 @@ BOOL PathGetSiblingFilePath(LPWSTR desti
         LogFinish(); \
         return retCode; \
       } \
   }
 #endif
 
 //-----------------------------------------------------------------------------
 
-// This variable lives in libbz2.  It's declared in bzlib_private.h, so we just
-// declare it here to avoid including that entire header file.
-#define BZ2_CRC32TABLE_UNDECLARED
-
-#if MOZ_IS_GCC || defined(__clang__)
-extern "C"  __attribute__((visibility("default"))) unsigned int BZ2_crc32Table[256];
-#undef BZ2_CRC32TABLE_UNDECLARED
-#elif defined(__SUNPRO_C) || defined(__SUNPRO_CC)
-extern "C" __global unsigned int BZ2_crc32Table[256];
-#undef BZ2_CRC32TABLE_UNDECLARED
-#endif
-#if defined(BZ2_CRC32TABLE_UNDECLARED)
-extern "C" unsigned int BZ2_crc32Table[256];
-#undef BZ2_CRC32TABLE_UNDECLARED
-#endif
-
-static unsigned int
-crc32(const unsigned char *buf, unsigned int len)
-{
-  unsigned int crc = 0xffffffffL;
-
-  const unsigned char *end = buf + len;
-  for (; buf != end; ++buf)
-    crc = (crc << 8) ^ BZ2_crc32Table[(crc >> 24) ^ *buf];
-
-  crc = ~crc;
-  return crc;
-}
-
-//-----------------------------------------------------------------------------
-
 // A simple stack based container for a FILE struct that closes the
 // file descriptor from its destructor.
 class AutoFile
 {
 public:
   explicit AutoFile(FILE* file = nullptr)
     : mFile(file) {
   }
@@ -1522,19 +1491,17 @@ PatchFile::LoadSourceFile(FILE* ofile)
       return READ_ERROR;
     }
 
     r -= c;
     rb += c;
   }
 
   // Verify that the contents of the source file correspond to what we expect.
-
-  unsigned int crc = crc32(buf, header.slen);
-
+  uint32_t crc = lzma_crc32(buf, header.slen, 0);
   if (crc != header.scrc32) {
     LOG(("LoadSourceFile: destination file crc %d does not match expected " \
          "crc %d", crc, header.scrc32));
     return CRC_ERROR;
   }
 
   return OK;
 }