This support is only in git master (and was missing one ftbfs fix commit when I checked last night).
directhex@asachi:~/mono$ ./mono/mini/mono --version
Mono JIT compiler version 4.5.0 (arm64/5f05c5f Thu Mar 31 16:47:38 UTC 2016)
Copyright (C) 2002-2014 Novell, Inc, Xamarin Inc and Contributors.
www.mono-project.com
TLS: __thread
SIGSEGV: normal
Notifications: epoll
Architecture: arm64
Disabled: none
Misc: softdebug
LLVM: supported, not enabled.
GC: sgen
