diff --git a/noxfile.py b/noxfile.py
index 8199b64a681..f04dd8cc379 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -236,11 +236,15 @@ def coverage(session: nox.Session) -> None:
 
     if not os.path.exists(".coverage-output"):
         os.mkdir(".coverage-output")
+
+    # Parallelize coverage as much as possible, by default.
+    arguments = session.posargs or ["-n", "auto"]
+
     session.run(
         "pytest",
         "--cov=pip",
         "--cov-config=./setup.cfg",
-        *session.posargs,
+        *arguments,
         env={
             "COVERAGE_OUTPUT_DIR": "./.coverage-output",
             "COVERAGE_PROCESS_START": os.fsdecode(Path("setup.cfg").resolve()),