We introduce the problem of generating musical leadsheets, i.e. a melody with chord labels, in the style of an arbitrary composer, that satisfy arbitrary user constraints. The problem is justified by the very nature of musical creativity, as many composers create music precisely by imitating a given style to which they add their own constraints. We propose a solution of this problem by formulating it as a Markov constraint problem. Markov constraints enable users to create stylistically imitative leadsheets that satisfy a large palette of constraints. We show that generated leadsheets are stylistically consistent by reclassifying them using Markov classifiers.