It is challenging to develop highly efficient and extremely clean engines, while meeting user expectations in terms of performance, comfort and driveability. One of the critical aspects in this regard is combustion noise control. Combustion noise represents about 40 percent of the overall engine noise in typical turbocharged diesel engines. The understanding of noise generation is intricate due to its inherent complexity and measurement limitations. Therefore, current efforts are focused on developing efficient strategies to understand the combustion noise mechanisms in order to reduce engine noise while maintaining high efficiency and low pollutant emissions. In the present work, a methodology was developed which combined computational fluid dynamics (CFD) modeling and genetic algorithm (GA) technique to optimize the combustion system hardware design of a high-speed direct injection (HSDI) diesel engine, with respect to various emissions and performance targets including combustion noise. The CFD model was specifically set up for reproducing the unsteady pressure field inside the combustion chamber, thereby allowing an accurate prediction of the acoustic response of the combustion phenomena. The model was validated by simulating several steady operation conditions and comparing the results against experimental data, in both temporal and frequency domains. The optimization goal was to minimize indicated specific fuel consumption (ISFC) and combustion noise, while restricting pollutant (soot and NOx) emissions to the baseline values. An objective merit function was constructed to quantify the strength of the designs. Eight design variables were selected including piston bowl geometry, spray inclusion angle, number of injector nozzle holes and in-cylinder swirl. The in-cylinder noise level was characterized by the total resonance energy of local pressure fluctuations. The optimum engine configuration thus obtained, showed a significant improvement in terms of efficiency and combustion noise compared to the baseline combustion system, and limiting emissions within their respective constraints. This optimum configuration included a deeper and tighter bowl geometry with higher swirl and greater number of nozzle holes. Subsequently, a sequential analysis was also performed to assess the influence of each design parameter on different targets. This study demonstrated an effective way of incorporating combustion noise into a numerical optimization strategy for engine design.