diff --git a/lld/test/lit.cfg.py b/lld/test/lit.cfg.py
--- a/lld/test/lit.cfg.py
+++ b/lld/test/lit.cfg.py
@@ -101,11 +101,13 @@
 
 tar_executable = lit.util.which('tar', config.environment['PATH'])
 if tar_executable:
+    env = os.environ
+    env['LANG'] = 'C'
     tar_version = subprocess.Popen(
         [tar_executable, '--version'],
         stdout=subprocess.PIPE,
         stderr=subprocess.PIPE,
-        env={'LANG': 'C'})
+        env=env)
     sout, _ = tar_version.communicate()
     if 'GNU tar' in sout.decode():
         config.available_features.add('gnutar')