A computer-implemented design flow can include, within a circuit design for an integrated circuit, determining a portion of the circuit design that is a candidate for implementation as a runtime customizable circuit and determining implementation options for the runtime customizable circuit. The design flow can also include generating, using computer hardware, a description of the circuit design using the runtime customizable circuit to implement the portion of the circuit design and generating, using the computer hardware, program code for an embedded processor coupled to an implementation of the runtime customizable circuit within the integrated circuit. The program code is usable by the embedded processor to parameterize the runtime customizable circuit to create a specific instance of the runtime customizable circuit.