The HEVC (High Efficiency Video Coding) standard brings the necessary quality versus rate performance for efficient transmission of Ultra High Definition formats (UHD). However, one of the remaining barriers to its adoption for UHD content is the high encoding complexity. In this paper, we address the problem of HEVC encoding complexity reduction by proposing a strategy to infer UHD coding modes and quad-tree from those optimized on the lower (HD) resolution version of the input video. A speed-up by a factor of 3 is achieved compared to directly encoding the UHD format at the expense of a limited quality loss.