The Object Constraint Language (OCL) is a central component in modeling and transformation languages such as the Unified Modeling Language (UML), the Meta Object Facility (MOF), and Query View Transformation (QVT). OCL is standardized as a strict functional language. In this article, we propose a lazy evaluation strategy for OCL. We argue that a lazy evaluation semantics is beneficial in some model-driven engineering scenarios for: i) lowering evaluation times on very large models; ii) simplifying expressions on models by using infinite data structures (e.g., infinite models); iii) increasing the reusability of OCL libraries. We implement the approach on the ATL virtual machine EMFTVM.