Automatic preprocessing for black box translation

Various embodiments set forth systems and techniques for training a sentence preprocessing model. The techniques include determining, using a machine translation system, a back translation associated with a ground truth translation of a source sentence in a source language to a target language, wherein the back translation comprises a translation of the ground truth translation from one or more target languages to the source language; determining, using the sentence preprocessing model, a simplified sentence associated with the source sentence; and updating one or more parameters of the sentence preprocessing model based on the simplified sentence and the back translation.