During the last year a modified baseline design for the E-ELT has been developed. The aim of this revision was both to achieve a significant cost saving and to reduce risk on major items. The primary mirror diameter was slightly reduced to 39 m and the total height of the telescope also decreased accordingly. This paper describes the work performed by ESO and a variety of contractors to review the EELT design to match the modified baseline. Detailed design and construction planning, as well as detailed cost estimates were updated for the 39-metre baseline design. In June 2011, ESO Council formally endorsed this modified design as the E-ELT revised baseline. The design drivers and balancing cost factors will be described along with the risk reduction measures taken during this phase. This will culminate in the design which has been agreed as being ready to move forward to construction once approval from ESO Council has been achieved.