A system for treating a body vessel may include a delivery device and a prosthesis retained on the delivery device. The prosthesis may include a main body and first and second legs each extending from the main body. The main body may include a lumen, and the first leg may include a lumen in fluid communication with the lumen of the main body. The second leg may include a tubular graft body and a stent attached to the graft body. The prosthesis may have a predeployment configuration in which the graft body of the second leg is inverted into and positioned within the lumen of the first leg, and the stent is positioned outside of the inverted graft body. The prosthesis may have a deployed configuration in which the second leg extends outward from the main body, and the stent is positioned within a lumen of the graft body.