As real-time embedded systems become more complex, there is the need to build them using high performance commercial off-The-shelf (COTS) components. However, tasks can exhibit hard to predict worst case execution times (WCET) when executing on commodity hardware, due to contention among shared physical resources. Past work has introduced the PRedictable Execution Model (PREM)  to solve this issue, but unfortunately, the time required to manually refactor existing code according to this model is too high. Light-PREM proposes a novel technique that automates the refactoring process needed to convert legacy software applications to PREM-compliant code. The advantage of Light-PREM is twofold. On one side, it makes the adoption of PREM more attractive from an industrial point of view, because it significantly reduces the amount of work that is needed to generate PREM-compliant code. On the other hand, the proposed methodology is general enough to be used with any embedded software design. Experimental results show that Light-PREM significantly improves the predictability of real-time applications without requiring software engineers to gain a deep understanding about software memory usage.