Also have this issue when trying to compile for i386-w64-mingw32, x86_64-w64-mingw32 is fine.

example:

/home/user/Downloads/ellcc/bin/ecc -target i386-w64-mingw32 -o hello.exe hello.c
In file included from hello.c:1:
/home/user/Downloads/ellcc/bin/../libecc/include/stdio.h:22:10: fatal error: 
      'bits/alltypes.h' file not found
#include <bits/alltypes.h>
         ^
1 error generated.

hello.c:

#include <stdio.h>

main() { printf("hello, world\n"); }

Using precompiled ellcc-x86_64-linux-0.1.30. Last time I compiled for i386 Windows was around July 2015 using whatever the latest ELLCC release was then, so I’m not when this started happening. Am I perhaps just missing something embarrassingly simple?