You're looking for qemu-system-x86_64. Note that using it may or may not be legal, depending on jurisdiction and emulated CPU model, due to Intel/AMD x86 ISA patents / copyrights.
On the other hand, using QEMU to emulate OpenPOWER, RISC-V, SPARC, etc. should be perfectly clear (might want to verify SPARC ISA status, IANAL etc.).