diff --git a/testing/mozharness/configs/repackage/osx_signed.py b/testing/mozharness/configs/repackage/osx_signed.py
index 77bad59279c0..8fccac4ef60c 100644
--- a/testing/mozharness/configs/repackage/osx_signed.py
+++ b/testing/mozharness/configs/repackage/osx_signed.py
@@ -2,16 +2,23 @@ import os
 
 config = {
     "input_home": "{abs_work_dir}/inputs",
+    "output_home": "{abs_work_dir}/artifacts",
     "src_mozconfig": "browser/config/mozconfigs/macosx64/repack",
 
     "download_config": {
         "target.tar.gz": os.environ.get("SIGNED_INPUT"),
+        "mar": os.environ.get("UNSIGNED_MAR"),
     },
 
     "repackage_config": [[
         "dmg",
         "-i", "{abs_work_dir}/inputs/target.tar.gz",
         "-o", "{output_home}/target.dmg"
+    ], [
+        "mar",
+        "-i", "{abs_work_dir}/inputs/target.tar.gz",
+        "--mar", "{abs_work_dir}/inputs/mar",
+        "-o", "{output_home}/target.complete.mar"
     ]],
 
     # ToolTool
diff --git a/testing/mozharness/scripts/repackage.py b/testing/mozharness/scripts/repackage.py
index 02b6a007be4d..d0a37cdd191c 100644
--- a/testing/mozharness/scripts/repackage.py
+++ b/testing/mozharness/scripts/repackage.py
@@ -37,6 +37,10 @@ class Repackage(BaseScript):
             if not status:
                 self.fatal("Unable to fetch signed input from %s" % url)
 
+            if 'mar' in path:
+                # Ensure mar is executable
+                self.chmod(os.path.join(input_home, path), 0755)
+
     def setup(self):
         self._run_tooltool()
         self._get_mozconfig()
@@ -46,13 +50,14 @@ class Repackage(BaseScript):
         if self.abs_dirs:
             return self.abs_dirs
         abs_dirs = super(Repackage, self).query_abs_dirs()
+        config = self.config
         for directory in abs_dirs:
             value = abs_dirs[directory]
             abs_dirs[directory] = value
         dirs = {}
         dirs['abs_tools_dir'] = os.path.join(abs_dirs['abs_work_dir'], 'tools')
         dirs['abs_mozilla_dir'] = os.path.join(abs_dirs['abs_work_dir'], 'src')
-        dirs['output_home'] = os.path.join(abs_dirs['abs_work_dir'], 'artifacts')
+        dirs['output_home'] = config['output_home'].format(**abs_dirs)
         for key in dirs.keys():
             if key not in abs_dirs:
                 abs_dirs[key] = dirs[key]