1. A computer program product for implementing an instruction loop buffer, the computer program product comprising: a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method comprising: fetching instructions from memory to generate an internal instruction to be executed; determining, by a processor, that a first instruction from the instructions corresponds to a first instruction loop; determining that a first internal instruction loop corresponding to the first instruction loop is not stored in a loop buffer; optimizing one or more internal instructions of the first instruction loop; and storing a resulting first optimized internal instruction loop in the loop buffer based on the determining that the first internal instruction loop is not stored in the loop buffer.