Modern software systems adapt themselves to changing environments in order to meet quality-of-service requirements, such as response time limits. The engineering of the system's self-adaptation logic does not only require new modeling methods, but also new analysis of transient phases. Model-driven software performance engineering methods already allow design-time analysis of steady states of nonadaptive system models. In order to validate requirements for transient phases, new modeling and analysis methods are needed. In this paper, we present SimuLizar, our initial model-driven approach to model self-adaptive systems and to analyze the performance of their transient phases. Our evaluation of a proof of concept load balancer system shows the applicability of our modeling approach. In addition, a comparison of our performance analysis with a prototypical implementation of our example system provides evidence that the prediction accuracy is sufficient to identify unsatisfactory self-adaptations.