+dnl **************
+dnl *** NaCl ***
+dnl **************
+
+AC_ARG_ENABLE(nacl_codegen, [ --enable-nacl-codegen Enable Native Client code generation], enable_nacl_codegen=$enableval, enable_nacl_codegen=no)
+AC_ARG_ENABLE(nacl_gc, [ --enable-nacl-gc Enable Native Client garbage collection], enable_nacl_gc=$enableval, enable_nacl_gc=no)
+
+AM_CONDITIONAL(NACL_CODEGEN, test x$enable_nacl_codegen != xno)
+if test "x$enable_nacl_codegen" = "xyes"; then
+ MONO_NACL_ALIGN_MASK_OFF=1
+ CPPFLAGS="$CPPFLAGS -D__native_client_codegen__"
+ AC_DEFINE(TARGET_NACL, 1, [...])
+else
+ MONO_NACL_ALIGN_MASK_OFF=0
+ CPPFLAGS="$CPPFLAGS -D__default_codegen__"
+fi
+if test "x$enable_nacl_gc" = "xyes"; then
+ CPPFLAGS="$CPPFLAGS -finstrument-for-thread-suspension -D__native_client_gc__"
+fi
+AC_SUBST(MONO_NACL_ALIGN_MASK_OFF)
+