A method comprises providing a non-transitory, machine-readable storage medium storing a partial netlist of at least a portion of a previously taped-out integrated circuit (IC) layout, representing a set of photomasks for fabricating an IC having the IC layout such that the IC meets a first specification value. A computer identifies a proper subset of a plurality of first devices in the IC layout, such that replacement of the proper subset of the first devices by second devices in a revised IC layout satisfies a second specification value different from the first specification value. At least one layout mask is generated and stored in at least one non-transitory machine readable storage medium, accessible by a tool for forming at least one additional photomask, such that the set of photomasks and the at least one additional photomask are usable to fabricate an IC according to the revised IC layout.