Ford is working to integrate its autonomous cars with Lyft's ride-hailing software so someday Ford can carry Lyft passengers.

The two companies will link their software in a partnership announced Wednesday.

At first human-driven cars from Ford will carry Lyft passengers. The automaker plans to connect its self-driving test cars to Lyft's network. But they won't carry passengers until they're fully tested. The companies didn't give a time frame for integrating services.

Ford says it expects the Lyft partnership to accelerate its self-driving car efforts. The company has said it wants to develop a fully driverless vehicle by 2021.

In July Lyft announced it would open its network to other companies for research. Lyft also has partnerships with Google's Waymo autonomous car unit and General Motors.