In many applications, subsequent data manipulations differ only in a small set of parameter values. Because of their reconfigurability, FPGAs (field programmable gate arrays) can be configured with an optimized configuration every time the parameter values change. These optimized configurations are smaller and faster than their generic counterparts. However, the overhead involved in generating the configurations at run-time with conventional tools is very large. This paper introduces an automatic method for generating runtime parameterizable configurations from arbitrary Boolean circuits. These configurations in which some of the configuration bits are expressed as a function of a set of parameters enable very fast run-time specialization since specialization only involves evaluating these functions. Our approach is validated on adaptive filtering. We show that the specialized filter configurations produced by our method are 2.3 times smaller and 36% faster than a generic filter configuration and that these configurations can be generated in on average 166 mus. Being a generic method, run-time hardware optimization suddenly becomes feasible for a large class of applications.