Our research is concerned with compiler-independent, tag-free garbage collection for the C++ programming language. We have previously presented a copying collector based on root registration. This paper presents a mark-and-sweep garbage collector that ameliorates shortcomings of the previous collector. We describe the two collectors and discuss why the new one is an improvement over the old one. We have tested this collector and a conservative collector in a VLSI CAD application, and this paper discusses the differences. Currently this prototype of the collector imposes too much overhead on our application. We intend to solve that problem, and then use the techniques described in this paper to implement a generational Mark-and-Sweep collector for C++.