It looks like some dependency on mkpeephole is probably wrong, as it was in use when it was rebuilt.

[9575->15059/24656 ~22] LINK mkpeephole.exe mkpeephole.exe.pdb
FAILED: mkpeephole.exe mkpeephole.exe.pdb
c:/src/depot_tools/python276_bin/python.exe ../../build/toolchain/win/tool_wrapper.py link-wrapper environment.x86 False link.exe /nologo /OUT:./mkpeephole.exe /PDB:./mkpeephole.exe.pdb @./mkpeephole.exe.rsp
LINK :Removed file: obj/v8/v8_libbase/platform-win32.obj
LINK :Removed file: obj/v8/v8_libbase/stack_trace_win.obj
LINK :Removed file: obj/v8/v8_libbase/random-number-generator.obj
LINK :Removed file: obj/v8/v8_libbase/sys-info.obj
LINK :Removed file: obj/v8/v8_libbase/time.obj
LINK :Removed file: obj/v8/v8_libbase/semaphore.obj
LINK :Removed file: obj/v8/v8_libbase/mutex.obj
LINK :Removed file: obj/v8/v8_libbase/condition-variable.obj
LINK :Removed file: obj/v8/v8_libbase/once.obj
LINK :Removed file: obj/v8/v8_libbase/logging.obj
LINK :Removed file: obj/v8/v8_libbase/ieee754.obj
LINK :Removed file: obj/v8/v8_libbase/functional.obj
LINK :Removed file: obj/v8/v8_libbase/file-utils.obj
LINK :Removed file: obj/v8/v8_libbase/division-by-constant.obj
LINK :Removed file: obj/v8/v8_libbase/stack_trace.obj
LINK :Removed file: obj/v8/v8_libbase/cpu.obj
LINK :Removed file: obj/v8/v8_libbase/bits.obj
LINK :Removed file: obj/v8/v8_libbase/atomicops_internals_x86_gcc.obj
LINK :New file: v8_libbase.dll.lib
LINK : object file added; performing full link
LINK : fatal error LNK1104: cannot open file './mkpeephole.exe'


I don't have a reliable repro yet.