A memory controller includes an I/O circuit, a read latency detector and a clock domain synchronizer. The I/O circuit transmits a first signal to a semiconductor memory device, receives a reflected signal returned from the semiconductor memory device, and delays the reflected signal in response to a delay selection signal to generate a second signal. The reflected signal is provided by reflection of the first signal from the semiconductor memory device. The read latency detector generates the first signal in response to a system clock signal, and generates a read latency signal in response to the system clock signal, a hold signal, and the second signal. The clock domain synchronizer generates the delay selection signal and the hold signal in response to the system clock signal and the second signal.