Two-dimensional (2D) materials such as monolayer molybdenum disulfide (MoS2) are extremely interesting for integration in nanoelectronic devices where they represent the ultimate limit of miniaturization in the vertical direction. Thanks to the presence of a band gap and subnanometer thickness, monolayer MoS2 can be used for the fabrication of transistors exhibiting extremely high on/off ratios and very low power dissipation. Here, we report on the development of 2D MoS2 transistors with improved performance due to enhanced electrostatic control. Our devices show currents in the 100 mu A/mu m range and transconductance exceeding 20 mu S/mu m as well as current saturation. We also record electrical breakdown of our devices and find that MoS2 can support very high current densities, exceeding the current-carrying capacity of copper by a factor of 50. Our results push the performance limit of MoS2 and open the way to their use in low-power and low-cost analog and radio frequency circuits.