This work presents a new energy saving technique for modern digital designs. We propose Time Interleaved Multi-Rail (TIMR) - a method for providing two dynamic supply rails to a circuit. This technique uses the first supply rail to mask the transition delay while changing the voltage of the second rail. We examine the design of TIMR as well as the implementation and considerations. We propose a number of control schemes that range from traditional DVFS to "race to sleep". This thesis also shows simulations of the technique using a existing voltage regulator in order to find the time and energy overhead of implementing the design. We find a 100μs switching time delay and 118μJ energy overhead associated with changing the voltage rail. This work concludes with comparisons to current energy saving techniques.