--- a/xpcom/build/PoisonIOInterposerMac.cpp
+++ b/xpcom/build/PoisonIOInterposerMac.cpp
@@ -1,16 +1,19 @@
 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
 /* 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 "PoisonIOInterposer.h"
+// Disabled until bug 1658385 is fixed.
+#ifndef __aarch64__
 #include "mach_override.h"
+#endif
 
 #include "mozilla/ArrayUtils.h"
 #include "mozilla/Assertions.h"
 #include "mozilla/DebugOnly.h"
 #include "mozilla/IOInterposer.h"
 #include "mozilla/Mutex.h"
 #include "mozilla/ProcessedStack.h"
 #include "mozilla/Telemetry.h"
@@ -321,19 +324,21 @@ void InitPoisonIOInterposer() {
   for (int i = 0; i < NumFunctions; ++i) {
     FuncData* d = Functions[i];
     if (!d->Function) {
       d->Function = dlsym(RTLD_DEFAULT, d->Name);
     }
     if (!d->Function) {
       continue;
     }
+#ifndef __aarch64__
     DebugOnly<mach_error_t> t =
         mach_override_ptr(d->Function, d->Wrapper, &d->Buffer);
     MOZ_ASSERT(t == err_none);
+#endif
   }
 }
 
 void OnlyReportDirtyWrites() { sOnlyReportDirtyWrites = true; }
 
 // Never called! See bug 1647107.
 void ClearPoisonIOInterposer() {
   // Not sure how or if we can unpoison the functions. Would be nice, but no

--- a/xpcom/build/moz.build
+++ b/xpcom/build/moz.build
@@ -36,18 +36,19 @@ if CONFIG['OS_ARCH'] == 'WINNT':
         'PoisonIOInterposerBase.cpp',
         'PoisonIOInterposerWin.cpp',
     ]
 elif CONFIG['MOZ_WIDGET_TOOLKIT'] == 'cocoa':
     UNIFIED_SOURCES += [
         'PoisonIOInterposerBase.cpp',
         'PoisonIOInterposerMac.cpp',
     ]
-    SOURCES += ['mach_override.c']
-    SOURCES['mach_override.c'].flags += ['-Wno-unused-function']
+    if CONFIG['CPU_ARCH'] != 'aarch64':
+        SOURCES += ['mach_override.c']
+        SOURCES['mach_override.c'].flags += ['-Wno-unused-function']
 else:
     SOURCES += ['PoisonIOInterposerStub.cpp']
 
 include('../glue/objs.mozbuild')
 
 XPCOM_MANIFESTS += [
     'components.conf',
 ]