You're measuring the size of a program that calls GCC, not GCC itself at all. gcc-5 isn't the compiler, it dispatches to cpp/cc1/ld/etc. cc1 is 20MB over here.

You're measuring the size of a program that calls GCC, not GCC itself at all. gcc-5 isn't the compiler, it dispatches to cpp/cc1/ld/etc. cc1 is 20MB over here. gold is 5MB. Dynamic libraries it depends on (gmp & family, isl) weigh about 4MB. All-in-all the programs required to compile even a simple C program come out around ~32MB. Clang is much bigger. Clang 3.8 is 59MB (I think that includes the preprocessor though, but GNU's CPP is only around 1MB (which still seems huge for a preprocessor)).