We investigate the effects of quantized beamforming on the capacity of a Massive MIMO by deriving explicit performance formulas. Our approach is applicable to a large class of quantizations, including PSK, QAM and polar quantizations. We show that with any degree of quantization, the beamforming gain grows linearly with the number of transmit antennas. Our results have important implications for the practical design and implementation of Massive MIMO as they indicate quantitatively the feasibility of highly economical A/D and D/A converters with very low resolutions.