Variability management is a key concern in the software industry. It allows designers to rapidly propose applications that fit the environment and the user needs, with a certain Quality-of-Service level, by choosing adapted variants. While Aspect-Oriented Programming has been introduced for managing variability and complexity at the code level, the Software Product-Line community highlights the needs for variability in the earlier phases of the software lifecycle, where a system is generally described by means of models. In this paper, we propose a generic approach for weaving flexible and reusable aspects at a model level. By extending our generic Aspect-Oriented Modeling approach with variability, we can manage variability and complexity in the early phases of the software lifecycle.