diff --git a/.gitignore b/.gitignore
index e572afb4dd9..511177abdc4 100644
--- a/.gitignore
+++ b/.gitignore
@@ -83,8 +83,6 @@ src/client/no-git-version
 src/core/developer
 src/manifest/dune
 src/manifest/install.inc
-src/stubs/libacl/dune
-src/stubs/libacl/c-libraries.sexp
 src/stubs/win32/cc64
 src/stubs/win32/dune
 src/stubs/c-flags.sexp
diff --git a/Makefile b/Makefile
index 9ba7c088aa3..1a60ac4a015 100644
--- a/Makefile
+++ b/Makefile
@@ -96,7 +96,7 @@ clean:
 distclean: clean clean-ext
 	rm -rf autom4te.cache bootstrap
 	rm -f Makefile.config config.log config.status aclocal.m4
-	rm -f src/*.META src/*/.merlin src/manifest/dune src/manifest/install.inc src/stubs/libacl/dune src/stubs/win32/dune src/stubs/win32/cc64 src/ocaml-flags-configure.sexp src/stubs/libacl/c-libraries.sexp
+	rm -f src/*.META src/*/.merlin src/manifest/dune src/manifest/install.inc src/stubs/win32/dune src/stubs/win32/cc64 src/ocaml-flags-configure.sexp
 	rm -f src/client/linking.sexp src/stubs/c-flags.sexp src/core/developer src/core/version
 
 OPAMINSTALLER_FLAGS = --prefix "$(call CYGPATH,$(DESTDIR)$(prefix))"
diff --git a/configure b/configure
index 6a916830055..9bc9fbc7333 100755
--- a/configure
+++ b/configure
@@ -615,38 +615,6 @@ PACKAGE_BUGREPORT=''
 PACKAGE_URL=''
 
 ac_default_prefix=`echo "os_type: ${OCAML_OS_TYPE}" | sed -e "s;^os_type: Win32;C:/OPAM;" -e "s;^os_type:.*;/usr/local;"`
-# Factoring default headers for most tests.
-ac_includes_default="\
-#include <stddef.h>
-#ifdef HAVE_STDIO_H
-# include <stdio.h>
-#endif
-#ifdef HAVE_STDLIB_H
-# include <stdlib.h>
-#endif
-#ifdef HAVE_STRING_H
-# include <string.h>
-#endif
-#ifdef HAVE_INTTYPES_H
-# include <inttypes.h>
-#endif
-#ifdef HAVE_STDINT_H
-# include <stdint.h>
-#endif
-#ifdef HAVE_STRINGS_H
-# include <strings.h>
-#endif
-#ifdef HAVE_SYS_TYPES_H
-# include <sys/types.h>
-#endif
-#ifdef HAVE_SYS_STAT_H
-# include <sys/stat.h>
-#endif
-#ifdef HAVE_UNISTD_H
-# include <unistd.h>
-#endif"
-
-ac_header_c_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
 VENDORED
@@ -687,7 +655,6 @@ PATH_PREPEND
 CC64
 CONF_CFLAGS
 CONF_OCAMLFLAGS
-CONF_LIBACL_LINK
 MCCS_ENABLED
 DEVELOPER
 OBJEXT
@@ -767,7 +734,6 @@ enable_checks
 enable_developer_mode
 with_mccs
 with_0install_solver
-with_libacl
 with_private_runtime
 enable_static
 enable_cold_check
@@ -1428,7 +1394,6 @@ Optional Packages:
   --without-0install-solver
                           Legacy option (does nothing)
 
-  --with-libacl           Compile opam with libacl support
   --with-private-runtime  For a mingw-w64 build, manifest the runtime DLLs
                           locally in Opam.Runtime.arch
   --without-dune          Compile using vendored Dune instead of any in PATH
@@ -1568,86 +1533,6 @@ fi
 
 } # ac_fn_c_try_compile
 
-# ac_fn_c_check_header_compile LINENO HEADER VAR INCLUDES
-# -------------------------------------------------------
-# Tests whether HEADER exists and can be compiled using the include files in
-# INCLUDES, setting the cache variable VAR accordingly.
-ac_fn_c_check_header_compile ()
-{
-  as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for $2" >&5
-printf %s "checking for $2... " >&6; }
-if eval test \${$3+y}
-then :
-  printf %s "(cached) " >&6
-else $as_nop
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-$4
-#include <$2>
-_ACEOF
-if ac_fn_c_try_compile "$LINENO"
-then :
-  eval "$3=yes"
-else $as_nop
-  eval "$3=no"
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
-fi
-eval ac_res=\$$3
-	       { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
-printf "%s\n" "$ac_res" >&6; }
-  eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno
-
-} # ac_fn_c_check_header_compile
-
-# ac_fn_c_try_link LINENO
-# -----------------------
-# Try to link conftest.$ac_ext, and return whether this succeeded.
-ac_fn_c_try_link ()
-{
-  as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack
-  rm -f conftest.$ac_objext conftest.beam conftest$ac_exeext
-  if { { ac_try="$ac_link"
-case "(($ac_try" in
-  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
-  *) ac_try_echo=$ac_try;;
-esac
-eval ac_try_echo="\"\$as_me:${as_lineno-$LINENO}: $ac_try_echo\""
-printf "%s\n" "$ac_try_echo"; } >&5
-  (eval "$ac_link") 2>conftest.err
-  ac_status=$?
-  if test -s conftest.err; then
-    grep -v '^ *+' conftest.err >conftest.er1
-    cat conftest.er1 >&5
-    mv -f conftest.er1 conftest.err
-  fi
-  printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
-  test $ac_status = 0; } && {
-	 test -z "$ac_c_werror_flag" ||
-	 test ! -s conftest.err
-       } && test -s conftest$ac_exeext && {
-	 test "$cross_compiling" = yes ||
-	 test -x conftest$ac_exeext
-       }
-then :
-  ac_retval=0
-else $as_nop
-  printf "%s\n" "$as_me: failed program was:" >&5
-sed 's/^/| /' conftest.$ac_ext >&5
-
-	ac_retval=1
-fi
-  # Delete the IPA/IPO (Inter Procedural Analysis/Optimization) information
-  # created by the PGI compiler (conftest_ipa8_conftest.oo), as it would
-  # interfere with the next link command; also delete a directory that is
-  # left behind by Apple's compiler.  We do this before executing the actions.
-  rm -rf conftest.dSYM conftest_ipa8_conftest.oo
-  eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno
-  as_fn_set_status $ac_retval
-
-} # ac_fn_c_try_link
-
 # ac_fn_cxx_try_compile LINENO
 # ----------------------------
 # Try to compile conftest.$ac_ext, and return whether this succeeded.
@@ -2289,15 +2174,6 @@ main (int argc, char **argv)
 }
 "
 
-as_fn_append ac_header_c_list " stdio.h stdio_h HAVE_STDIO_H"
-as_fn_append ac_header_c_list " stdlib.h stdlib_h HAVE_STDLIB_H"
-as_fn_append ac_header_c_list " string.h string_h HAVE_STRING_H"
-as_fn_append ac_header_c_list " inttypes.h inttypes_h HAVE_INTTYPES_H"
-as_fn_append ac_header_c_list " stdint.h stdint_h HAVE_STDINT_H"
-as_fn_append ac_header_c_list " strings.h strings_h HAVE_STRINGS_H"
-as_fn_append ac_header_c_list " sys/stat.h sys_stat_h HAVE_SYS_STAT_H"
-as_fn_append ac_header_c_list " sys/types.h sys_types_h HAVE_SYS_TYPES_H"
-as_fn_append ac_header_c_list " unistd.h unistd_h HAVE_UNISTD_H"
 # Test code for whether the C++ compiler supports C++98 (global declarations)
 ac_cxx_conftest_cxx98_globals='
 // Does the compiler advertise C++98 conformance?
@@ -4021,16 +3897,6 @@ fi
 
 
 
-# Check whether --with-libacl was given.
-if test ${with_libacl+y}
-then :
-  withval=$with_libacl;
-else $as_nop
-  with_libacl=auto
-fi
-
-
-
 # Check whether --with-private_runtime was given.
 if test ${with_private_runtime+y}
 then :
@@ -4973,143 +4839,6 @@ else $as_nop
 
 fi
 
-
-ac_header= ac_cache=
-for ac_item in $ac_header_c_list
-do
-  if test $ac_cache; then
-    ac_fn_c_check_header_compile "$LINENO" $ac_header ac_cv_header_$ac_cache "$ac_includes_default"
-    if eval test \"x\$ac_cv_header_$ac_cache\" = xyes; then
-      printf "%s\n" "#define $ac_item 1" >> confdefs.h
-    fi
-    ac_header= ac_cache=
-  elif test $ac_header; then
-    ac_cache=$ac_item
-  else
-    ac_header=$ac_item
-  fi
-done
-
-
-
-
-
-
-
-
-if test $ac_cv_header_stdlib_h = yes && test $ac_cv_header_string_h = yes
-then :
-
-printf "%s\n" "#define STDC_HEADERS 1" >>confdefs.h
-
-fi
-if test "x${with_libacl}" != "xno"
-then :
-
-  have_libacl=yes
-  ac_fn_c_check_header_compile "$LINENO" "acl/libacl.h" "ac_cv_header_acl_libacl_h" "$ac_includes_default"
-if test "x$ac_cv_header_acl_libacl_h" = xyes
-then :
-
-else $as_nop
-  have_libacl=no
-fi
-
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for library containing acl_get_perm" >&5
-printf %s "checking for library containing acl_get_perm... " >&6; }
-if test ${ac_cv_search_acl_get_perm+y}
-then :
-  printf %s "(cached) " >&6
-else $as_nop
-  ac_func_search_save_LIBS=$LIBS
-cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-
-/* Override any GCC internal prototype to avoid an error.
-   Use char because int might match the return type of a GCC
-   builtin and then its argument prototype would still apply.  */
-char acl_get_perm ();
-int
-main (void)
-{
-return acl_get_perm ();
-  ;
-  return 0;
-}
-_ACEOF
-for ac_lib in '' acl
-do
-  if test -z "$ac_lib"; then
-    ac_res="none required"
-  else
-    ac_res=-l$ac_lib
-    LIBS="-l$ac_lib  $ac_func_search_save_LIBS"
-  fi
-  if ac_fn_c_try_link "$LINENO"
-then :
-  ac_cv_search_acl_get_perm=$ac_res
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.beam \
-    conftest$ac_exeext
-  if test ${ac_cv_search_acl_get_perm+y}
-then :
-  break
-fi
-done
-if test ${ac_cv_search_acl_get_perm+y}
-then :
-
-else $as_nop
-  ac_cv_search_acl_get_perm=no
-fi
-rm conftest.$ac_ext
-LIBS=$ac_func_search_save_LIBS
-fi
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_search_acl_get_perm" >&5
-printf "%s\n" "$ac_cv_search_acl_get_perm" >&6; }
-ac_res=$ac_cv_search_acl_get_perm
-if test "$ac_res" != no
-then :
-  test "$ac_res" = "none required" || LIBS="$ac_res $LIBS"
-
-else $as_nop
-  have_libacl=no
-fi
-
-  if test "x${SYSTEM}" = "xcygwin"
-then :
-
-    if test "x${have_libacl}" = "xno"
-then :
-  as_fn_error $? "opam on Cygwin requires libacl" "$LINENO" 5
-else $as_nop
-  with_libacl=yes
-fi
-
-fi
-  if test "x${with_libacl}${have_libacl}" = "xyesno"
-then :
-  as_fn_error $? "libacl not found" "$LINENO" 5
-fi
-
-fi
-if test "x${with_libacl}" = "xyes"
-then :
-
-  if test "x${ac_cv_search_acl_get_perm}" = "xnone required"
-then :
-
-
-
-else $as_nop
-
-    CONF_LIBACL_LINK=${ac_cv_search_acl_get_perm}
-
-
-fi
-
-fi
-
 CONF_OCAMLFLAGS=''
 
 if test "x${CI}" != "x" -o "x${enable_developer_mode}" = "xyes"
@@ -7307,7 +7036,7 @@ if test "x$prefix" = "xNONE"; then
   prefix=$ac_default_prefix
 fi
 
-ac_config_files="$ac_config_files Makefile.config src/ocaml-flags-configure.sexp src/stubs/c-flags.sexp src/stubs/libacl/c-libraries.sexp"
+ac_config_files="$ac_config_files Makefile.config src/ocaml-flags-configure.sexp src/stubs/c-flags.sexp"
 
 cat >confcache <<\_ACEOF
 # This file is a shell script that caches the results of configure
@@ -8013,7 +7742,6 @@ do
     "Makefile.config") CONFIG_FILES="$CONFIG_FILES Makefile.config" ;;
     "src/ocaml-flags-configure.sexp") CONFIG_FILES="$CONFIG_FILES src/ocaml-flags-configure.sexp" ;;
     "src/stubs/c-flags.sexp") CONFIG_FILES="$CONFIG_FILES src/stubs/c-flags.sexp" ;;
-    "src/stubs/libacl/c-libraries.sexp") CONFIG_FILES="$CONFIG_FILES src/stubs/libacl/c-libraries.sexp" ;;
 
   *) as_fn_error $? "invalid argument: \`$ac_config_target'" "$LINENO" 5;;
   esac
@@ -8493,15 +8221,6 @@ then :
   ${LN_S} -f dune-win32 dune
   cd ../../..
 
-fi
-rm -f src/stubs/libacl/dune
-if  test "x${with_libacl}" = "xyes"
-then :
-
-  cd src/stubs/libacl
-  ${LN_S} -f dune-libacl dune
-  cd ../../..
-
 fi
 
 echo
diff --git a/configure.ac b/configure.ac
index 1dd909807d4..32f9c76353b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -69,9 +69,6 @@ AS_IF([test "x$with_0install_solver" = xno],
 )
 
 
-AC_ARG_WITH([libacl],
-  AS_HELP_STRING([--with-libacl],[Compile opam with libacl support]),,[with_libacl=auto])
-
 AC_ARG_WITH([private_runtime],
   AS_HELP_STRING([--with-private-runtime],[For a mingw-w64 build, manifest the runtime DLLs locally in Opam.Runtime.arch]),,[with_private_runtime=no]
 )
@@ -165,23 +162,6 @@ AS_IF([test "x${enable_developer_mode}" = "xyes"],[
 
 AS_IF([test "x${with_mccs}" = "xno"], [AC_SUBST(MCCS_ENABLED,false)], [AC_SUBST(MCCS_ENABLED,true)])
 
-AS_IF([test "x${with_libacl}" != "xno"],[
-  have_libacl=yes
-  AC_CHECK_HEADER([acl/libacl.h],,[have_libacl=no])
-  AC_SEARCH_LIBS([acl_get_perm],[acl],,[have_libacl=no])
-  AS_IF([test "x${SYSTEM}" = "xcygwin"],[
-    AS_IF([test "x${have_libacl}" = "xno"],[AC_MSG_ERROR([opam on Cygwin requires libacl])],[with_libacl=yes])
-  ])
-  AS_IF([test "x${with_libacl}${have_libacl}" = "xyesno"],[AC_MSG_ERROR([libacl not found])])
-])
-AS_IF([test "x${with_libacl}" = "xyes"],[
-  AS_IF([test "x${ac_cv_search_acl_get_perm}" = "xnone required"],[
-    AC_SUBST(CONF_LIBACL_LINK,[])
-  ],[
-    AC_SUBST(CONF_LIBACL_LINK,[${ac_cv_search_acl_get_perm}])
-  ])
-])
-
 CONF_OCAMLFLAGS=''
 
 AS_IF([test "x${CI}" != "x" -o "x${enable_developer_mode}" = "xyes"],[
@@ -449,7 +429,6 @@ AC_CONFIG_FILES(
   Makefile.config
   src/ocaml-flags-configure.sexp
   src/stubs/c-flags.sexp
-  src/stubs/libacl/c-libraries.sexp
 )
 AC_OUTPUT
 
@@ -471,12 +450,6 @@ AS_IF([ test ${WIN32} -eq 1],[
   ${LN_S} -f dune-win32 dune
   cd ../../..
 ])
-rm -f src/stubs/libacl/dune
-AS_IF([ test "x${with_libacl}" = "xyes" ],[
-  cd src/stubs/libacl
-  ${LN_S} -f dune-libacl dune
-  cd ../../..
-])
 
 echo
 
diff --git a/master_changes.md b/master_changes.md
index ccd176df09f..78133f02909 100644
--- a/master_changes.md
+++ b/master_changes.md
@@ -141,3 +141,4 @@ users)
 ## opam-format
 
 ## opam-core
+  * Fix opam unable to find executables on systems where users belong to more than 32 groups when opam is built using musl libc [#5381 @kit-ty-kate - fix #5373]
diff --git a/src/core/dune b/src/core/dune
index 226611716d8..ebfd92e433d 100644
--- a/src/core/dune
+++ b/src/core/dune
@@ -4,9 +4,6 @@
   (synopsis    "OCaml Package Manager core internal stdlib")
   ; TODO: Remove (re_export ...) when CI uses the OCaml version that includes https://github.com/ocaml/ocaml/pull/11989
   (libraries   re (re_export ocamlgraph) unix sha jsonm swhid_core uutf
-               (select opamACL.ml from
-                       (opam-core.libacl -> opamACL.libacl.ml)
-                       (                 -> opamACL.dummy.ml))
                (select opamStubs.ml from
                        (opam-core.stubs -> opamStubs.win32.ml)
                        (                -> opamStubs.dummy.ml)))
diff --git a/src/core/opamACL.dummy.ml b/src/core/opamACL.dummy.ml
deleted file mode 100644
index 7d780f43da0..00000000000
--- a/src/core/opamACL.dummy.ml
+++ /dev/null
@@ -1,11 +0,0 @@
-(**************************************************************************)
-(*                                                                        *)
-(*    Copyright 2020 David Allsopp Ltd.                                   *)
-(*                                                                        *)
-(*  All rights reserved. This file is distributed under the terms of the  *)
-(*  GNU Lesser General Public License version 2.1, with the special       *)
-(*  exception on linking described in the file LICENSE.                   *)
-(*                                                                        *)
-(**************************************************************************)
-
-let get_acl_executable_info _ _ = None
diff --git a/src/core/opamACL.libacl.ml b/src/core/opamACL.libacl.ml
deleted file mode 100644
index 4cc599b5efc..00000000000
--- a/src/core/opamACL.libacl.ml
+++ /dev/null
@@ -1,11 +0,0 @@
-(**************************************************************************)
-(*                                                                        *)
-(*    Copyright 2020 David Allsopp Ltd.                                   *)
-(*                                                                        *)
-(*  All rights reserved. This file is distributed under the terms of the  *)
-(*  GNU Lesser General Public License version 2.1, with the special       *)
-(*  exception on linking described in the file LICENSE.                   *)
-(*                                                                        *)
-(**************************************************************************)
-
-include OpamlibACL
diff --git a/src/core/opamACL.mli b/src/core/opamACL.mli
deleted file mode 100644
index 4fb451be994..00000000000
--- a/src/core/opamACL.mli
+++ /dev/null
@@ -1,22 +0,0 @@
-(**************************************************************************)
-(*                                                                        *)
-(*    Copyright 2020 David Allsopp Ltd.                                   *)
-(*                                                                        *)
-(*  All rights reserved. This file is distributed under the terms of the  *)
-(*  GNU Lesser General Public License version 2.1, with the special       *)
-(*  exception on linking described in the file LICENSE.                   *)
-(*                                                                        *)
-(**************************************************************************)
-
-(** C auxiliary function used for POSIX 1003.1e DRAFT 17 permission checking. *)
-
-val get_acl_executable_info : string -> int -> int list option
-  (** If compiled without libacl support, this function always returns None
-      When opam is built with libacl support,
-      [get_acl_executable_info file owner] takes a filename and the uid of the
-      owner of that file (this is passed since the caller will have already
-      called {!Unix.stat}). The function returns [Some []] if the process can
-      execute [file] or [Some gids] if the process can execute [file] if one
-      of its groups matches [gids]. If the process cannot under any
-      circumstances execute [file] (or if an unexpected error occurred), then
-      [None] is returned. *)
diff --git a/src/core/opamStd.ml b/src/core/opamStd.ml
index ddcf8c3de41..2f9a449f9bc 100644
--- a/src/core/opamStd.ml
+++ b/src/core/opamStd.ml
@@ -1246,34 +1246,9 @@ module OpamSys = struct
   (* OCaml 4.05.0 no longer follows the updated PATH to resolve commands. This
      makes unqualified commands absolute as a workaround. *)
   let resolve_command =
-    let check_perms =
-      if Sys.win32 then fun f ->
-        try (Unix.stat f).Unix.st_kind = Unix.S_REG
-        with e -> fatal e; false
-      else fun f ->
-        try
-          let {Unix.st_uid; st_gid; st_perm; st_kind; _} = Unix.stat f in
-          if st_kind <> Unix.S_REG then false else
-          let groups =
-            IntSet.of_list (Unix.getegid () :: Array.to_list (Unix.getgroups ()))
-          in
-          let mask =
-            if Unix.geteuid () = (st_uid : int) then
-              0o100
-            else if IntSet.mem st_gid groups then
-              0o010
-            else
-              0o001
-          in
-          if (st_perm land mask) <> 0 then
-            true
-          else
-          match OpamACL.get_acl_executable_info f st_uid with
-          | None -> false
-          | Some [] -> true
-          | Some gids ->
-            not (IntSet.is_empty (IntSet.inter (IntSet.of_list gids) groups))
-        with e -> fatal e; false
+    let check_perms f =
+      try Unix.access f (Unix.R_OK :: if Sys.win32 then [] else [Unix.X_OK]); true
+      with Unix.Unix_error _ -> false
     in
     let resolve ?dir env name =
       if not (Filename.is_relative name) then begin
diff --git a/src/stubs/libacl/c-libraries.sexp.in b/src/stubs/libacl/c-libraries.sexp.in
deleted file mode 100644
index 3cb0baa5e78..00000000000
--- a/src/stubs/libacl/c-libraries.sexp.in
+++ /dev/null
@@ -1 +0,0 @@
-(@CONF_LIBACL_LINK@)
diff --git a/src/stubs/libacl/dune-libacl b/src/stubs/libacl/dune-libacl
deleted file mode 100644
index 93b27ee5833..00000000000
--- a/src/stubs/libacl/dune-libacl
+++ /dev/null
@@ -1,22 +0,0 @@
-(library
-  (name            opam_stubs_libacl)
-  (public_name     opam-core.libacl)
-  (synopsis        "OCaml Package Manager libacl C stubs")
-  (flags           (:standard
-                   (:include ../../ocaml-flags-standard.sexp)
-                   (:include ../../ocaml-flags-configure.sexp)
-                   (:include ../../ocaml-context-flags.sexp)))
-  (modules         opamlibACL)
-  (foreign_stubs
-    (language      c)
-    (names         opamACL)
-    (flags         :standard
-                   (:include ../c-flags.sexp)))
-  (c_library_flags :standard
-                   (:include c-libraries.sexp))
-  (wrapped         false))
-
-(rule
-  (targets c-libraries.sexp)
-  (mode    fallback)
-  (action  (with-stdout-to %{targets} (echo "()"))))
diff --git a/src/stubs/libacl/opamACL.c b/src/stubs/libacl/opamACL.c
deleted file mode 100644
index e9652868dfa..00000000000
--- a/src/stubs/libacl/opamACL.c
+++ /dev/null
@@ -1,127 +0,0 @@
-/**************************************************************************/
-/*                                                                        */
-/*    Copyright 2020 David Allsopp Ltd.                                   */
-/*                                                                        */
-/*  All rights reserved. This file is distributed under the terms of the  */
-/*  GNU Lesser General Public License version 2.1, with the special       */
-/*  exception on linking described in the file LICENSE.                   */
-/*                                                                        */
-/**************************************************************************/
-
-#include <unistd.h>
-#include <sys/types.h>
-#include <acl/libacl.h>
-
-#define CAML_NAME_SPACE
-#include <caml/mlvalues.h>
-#include <caml/alloc.h>
-#include <caml/memory.h>
-
-#ifndef Val_none
-#define Val_none Val_int(0)
-#endif
-
-/* OPAM_get_acl_executable_info(file, owner) takes a filename and the uid of
- * the file's owner (this saves a call to stat on both the OCaml and C sides).
- * The result is:
- *   None - the process cannot execute file
- *   Some [] - the process can execute file
- *   Some gids - the process can execute file if it is any of these gids
- */
-CAMLprim value OPAM_get_acl_executable_info(value file, value owner)
-{
-  CAMLparam2(file, owner);
-  CAMLlocal2(result, cell);
-  acl_t acl = acl_get_file(String_val(file), ACL_TYPE_ACCESS);
-  uid_t owner_uid = Int_val(owner);
-  uid_t uid = geteuid();
-
-  result = Val_none;
-
-  if (acl)
-  {
-    acl_entry_t entry;
-
-    if (acl_get_entry(acl, ACL_FIRST_ENTRY, &entry) == 1)
-    {
-      int mask = 1;
-      int user = 0;
-      do
-      {
-        acl_tag_t tag;
-        acl_permset_t perms;
-        if (acl_get_tag_type(entry, &tag) == 0 &&
-            acl_get_permset(entry, &perms) == 0)
-        {
-          void *qualifier = NULL;
-          int executable = acl_get_perm(perms, ACL_EXECUTE);
-
-          switch(tag)
-          {
-            case ACL_USER:
-              if (executable && (qualifier = acl_get_qualifier(entry)))
-              {
-                uid_t entry_uid = *((uid_t *)qualifier);
-                /* NB ACL_USER entries do not override ACL_USER_OBJ */
-                if (entry_uid != owner_uid && entry_uid == uid)
-                {
-                  /* result = Some [] */
-                  if (!Is_block(result))
-                  {
-                    result = caml_alloc_small(1, 0);
-                    Field(result, 0) = Val_int(0);
-                  } else {
-                    caml_modify(&Field(result, 0), Val_int(0));
-                  }
-                  user = 1;
-                }
-              }
-              break;
-            case ACL_GROUP:
-              if (!user && executable && (qualifier = acl_get_qualifier(entry)))
-              {
-                gid_t entry_gid = *((gid_t *)qualifier);
-                /* Construct a cons cell */
-                cell = caml_alloc_small(2, 0);
-                Field(cell, 0) = Val_int(entry_gid);
-                if (Is_block(result))
-                {
-                  /* Put cons cell at head of existing list */
-                  Field(cell, 1) = Field(result, 0);
-                  caml_modify(&Field(result, 0), cell);
-                }
-                else
-                {
-                  /* result = Some [cell] */
-                  Field(cell, 1) = Val_int(0);
-                  result = caml_alloc_small(1, 0);
-                  Field(result, 0) = cell;
-                }
-              }
-              break;
-            case ACL_USER_OBJ:
-            case ACL_GROUP_OBJ:
-              /* These have already been done by the stat check */
-              break;
-            case ACL_MASK:
-              if (!(mask = executable))
-              {
-                result = Val_none;
-              }
-              break;
-            default:
-              /* ACL_UNDEFINED_TAG or ACL_OTHER */
-              break;
-          }
-
-          if (qualifier)
-            acl_free(qualifier);
-        }
-      } while (mask && acl_get_entry(acl, ACL_NEXT_ENTRY, &entry) == 1);
-    }
-
-    acl_free((void *)acl);
-  }
-
-  CAMLreturn(result);
-}
diff --git a/src/stubs/libacl/opamlibACL.ml b/src/stubs/libacl/opamlibACL.ml
deleted file mode 100644
index a31e7cdf30e..00000000000
--- a/src/stubs/libacl/opamlibACL.ml
+++ /dev/null
@@ -1,11 +0,0 @@
-(**************************************************************************)
-(*                                                                        *)
-(*    Copyright 2020 David Allsopp Ltd.                                   *)
-(*                                                                        *)
-(*  All rights reserved. This file is distributed under the terms of the  *)
-(*  GNU Lesser General Public License version 2.1, with the special       *)
-(*  exception on linking described in the file LICENSE.                   *)
-(*                                                                        *)
-(**************************************************************************)
-
-external get_acl_executable_info : string -> int -> int list option = "OPAM_get_acl_executable_info"