During organogenesis, mesenchymal cell layers – such as smooth muscle cells in vertebrates – can actively shape organ morphology. We study muscle cells in Drosophila that sculpt the testis into a characteristic spiral. Knockdown of the adhesion G protein-coupled receptor Cirl/Latrophilin disrupts the alignment and collective migration of these cells, thereby affecting testis morphology. We investigate how Cirl/Latrophilin regulates the cytoskeleton and adhesion complexes at cell-cell interfaces to enable normal cell alignment and organ formation.