diff --git a/tools/lint/mach_commands.py b/tools/lint/mach_commands.py
index c644e5ab6376..7869928a7714 100644
--- a/tools/lint/mach_commands.py
+++ b/tools/lint/mach_commands.py
@@ -18,8 +18,16 @@ from mach.decorators import (
     Command,
 )
 
+try:
+    from os import scandir
+except ImportError:
+    from scandir import scandir
+
 
 here = os.path.abspath(os.path.dirname(__file__))
+GLOBAL_EXCLUDES = [
+    'tools/lint/test/files',
+]
 
 
 def setup_argument_parser():
@@ -27,6 +35,13 @@ def setup_argument_parser():
     return cli.MozlintParser()
 
 
+def get_global_excludes(topsrcdir):
+    excludes = GLOBAL_EXCLUDES[:]
+    excludes.extend([e.name for e in scandir(topsrcdir)
+                     if e.name.startswith('obj') and e.is_dir()])
+    return excludes
+
+
 @CommandProvider
 class MachCommands(MachCommandBase):
 
@@ -36,11 +51,12 @@ class MachCommands(MachCommandBase):
         parser=setup_argument_parser)
     def lint(self, *runargs, **lintargs):
         """Run linters."""
-        from mozlint import cli
-        lintargs.setdefault('root', self.topsrcdir)
-        lintargs['exclude'] = ['obj*', 'tools/lint/test/files']
-        cli.SEARCH_PATHS.append(here)
         self._activate_virtualenv()
+        from mozlint import cli
+
+        lintargs.setdefault('root', self.topsrcdir)
+        lintargs['exclude'] = get_global_excludes(lintargs['root'])
+        cli.SEARCH_PATHS.append(here)
         return cli.run(*runargs, **lintargs)
 
     @Command('eslint', category='devenv',