High Efficiency Video Coding (HEVC/H.265) is an emerging standard for video compression that provides almost double compression efficiency at the cost of major computational complexity increase as compared to current industry-standard Advanced Video Coding (AVC/H.264). This work proposes a collaborative hardware and software scheme for complexity reduction in an HEVC Intra encoding system, with run-time adaptivity. Our scheme leverages video content properties which drive the complexity management layer (software) to generate a highly probable coding configuration. The intra prediction size and direction are estimated for the prediction unit which provides reduced computational-complexity. At the hardware layer, specialized coprocessors with enhanced reusability are employed as accelerators. Additionally, depending upon the video properties, the software layer administers the energy management of the hardware coprocessors. Experimental results show that a complexity reduction of up to 60 % and the energy reduction up to 42 % are achieved.