The deformation behavior of individual grains in a large grained polycrystalline Cu sample is studied during in situ tensile loading. The Laue diffraction experiment was carried out at the EDDI beamline (Bessy II) using ultra-hard x-rays (5 to 160 keV) and a 3D energy dispersive pnCCD detector. The recorded Laue-patterns as a function of tensile loading show the evolution of spatially well-defined Laue spots into streaking ones. The pnCCD was used to record the position and the energy spectrum of each diffraction peak in all of the collected Laue patterns in a single shot experiment, which allowed to index all Laue spots and assign them to individual grains simultaneously. The two-fold information yields the crystal cell orientation of each individual grain and its relative orientation with respect to the surrounding grains, i.e. the texture of the probed region. Results show that the grains rotate around the loading axis until the preferred slip direction is aligned with the tensile direction. This phenomena is accompanied by a continuous expansion of the lattice parameters followed by a rapid strain release resulting in internal stress relaxation, while the strain increases again at very high strain levels.