A prefabricated lintel having two spaced apart parallel upstanding legs extending along the length of the lintel and having laterally aligned holes defined therethrough and spaced therealong. The lintel further has a flat lower surface and an upper surface defining flat, horizontal shoulders positioned along outer edges of the lintel on opposite sides of the upstanding legs and extending the length of the lintel. The lintel is placed to span a doorway and a course of blocks is laid on the flat shoulders, with a second course laid on the first course and a rebar positioned on the upper surface. A plurality of wire stirrups, each defining a rebar receiving loop, are engaged over the rebar and extend through openings in the two courses with end portions of the stirrups engaged in each of the holes defined in the upstanding legs of the lintel. The block openings are filled with grout.