A lateral tilt control system for an agricultural harvester may include first and second tilt cylinders coupled between a support structure and an implement of the harvester. The first tilt cylinder may include a first cap-side chamber and a first rod-side chamber and the second tilt cylinder may include a second cap-side chamber and a second rod-side chamber. The system may also include a first fluid line providing a flow path between the first cap-side chamber and the second rod-side chamber and a second fluid line providing a flow path between the first rod-side chamber and the second cap-side chamber. Additionally, the system may include a pressure relief valve coupled between the first and second fluid lines to allow fluid to be transferred between the first and second fluid lines when a fluid pressure within either fluid line exceeds a relief pressure setting.