At-speed testing of multi-die integrated circuits

An integrated circuit (IC) structure can include an interposer including a plurality of inter-die wires and a first die coupled to the interposer. The first die can include a first output including a first flip-flop coupled to a first inter-die wire of the plurality of inter-die wires and a first input including a second flip-flop coupled to a second inter-die wire of the plurality of inter-die wires. The IC structure can include a second die coupled to the interposer. The second die can be configured with a first circuit design forming circuitry that couples the first inter-die wire to the second inter-die wire.