--- a/python/mozbuild/mozbuild/backend/tup.py
+++ b/python/mozbuild/mozbuild/backend/tup.py
@@ -721,16 +721,23 @@ class TupBackend(CommonBackend):
         env.update({
             'MOZ_CARGO_WRAP_LDFLAGS': ' '.join(backend_file.local_flags['LDFLAGS']),
             'MOZ_CARGO_WRAP_LD': backend_file.environment.substs['CC'],
             linker_env_var: mozpath.join(self.environment.topsrcdir,
                                          'build', 'cargo-linker'),
             'RUSTFLAGS': '%s %s' % (' '.join(self.environment.substs['MOZ_RUST_DEFAULT_FLAGS']),
                                     ' '.join(self.environment.substs['RUSTFLAGS'])),
         })
+
+        if os.environ.get('MOZ_AUTOMATION'):
+            # Build scripts generally read environment variables that are set
+            # by cargo, however, some may rely on MOZ_AUTOMATION. We may need
+            # to audit for others as well.
+            env['MOZ_AUTOMATION'] = os.environ['MOZ_AUTOMATION']
+
         return env
 
     def _gen_cargo_rules(self, backend_file, build_plan, cargo_env):
         invocations = build_plan['invocations']
         processed = set()
 
         def get_libloading_outdir():
             for invocation in invocations: