diff --git a/mllib/common_utils.ml b/mllib/common_utils.ml
index 6a9b08973..60b43a3cc 100644
--- a/mllib/common_utils.ml
+++ b/mllib/common_utils.ml
@@ -846,29 +846,82 @@ let external_command ?(echo_cmd = true) cmd =
   );
   lines
 
-let run_command ?(echo_cmd = true) args =
-  if echo_cmd then
-    debug "%s" (stringify_args args);
+let rec run_commands ?(echo_cmd = true) cmds =
+  let res = Array.make (List.length cmds) 0 in
+  let pids =
+    mapi (
+      fun i (args, stdout_chan, stderr_chan) ->
+        let run_res = do_run args ?stdout_chan ?stderr_chan in
+        match run_res with
+        | Either (pid, app, outfd, errfd) ->
+          Some (i, pid, app, outfd, errfd)
+        | Or code ->
+          res.(i) <- code;
+          None
+    ) cmds in
+  let pids = filter_map identity pids in
+  let pids = ref pids in
+  while !pids <> [] do
+    let pid, stat = Unix.waitpid [] 0 in
+    let matching_pair, new_pids =
+      List.partition (
+        fun (_, p, _, _, _) ->
+          pid = p
+      ) !pids in
+    if matching_pair <> [] then (
+      let matching_pair = List.hd matching_pair in
+      let idx, _, app, outfd, errfd = matching_pair in
+      pids := new_pids;
+      res.(idx) <- do_teardown app outfd errfd stat
+    );
+  done;
+  Array.to_list res
+
+and run_command ?(echo_cmd = true) ?stdout_chan ?stderr_chan args =
+  let run_res = do_run args ~echo_cmd ?stdout_chan ?stderr_chan in
+  match run_res with
+  | Either (pid, app, outfd, errfd) ->
+    let _, stat = Unix.waitpid [] pid in
+    do_teardown app outfd errfd stat
+  | Or code ->
+    code
+
+and do_run ?(echo_cmd = true) ?stdout_chan ?stderr_chan args =
   let app = List.hd args in
+  let get_fd default = function
+    | None ->
+      default
+    | Some fd ->
+      Unix.set_close_on_exec fd;
+      fd
+  in
   try
     let app =
       if Filename.is_relative app then which app
       else (Unix.access app [Unix.X_OK]; app) in
-    let pid =
-      Unix.create_process app (Array.of_list args) Unix.stdin
-        Unix.stdout Unix.stderr in
-    let _, stat = Unix.waitpid [] pid in
-    match stat with
-    | Unix.WEXITED i -> i
-    | Unix.WSIGNALED i ->
-      error (f_"external command ‘%s’ killed by signal %d")
-        (stringify_args args) i
-    | Unix.WSTOPPED i ->
-      error (f_"external command ‘%s’ stopped by signal %d")
-        (stringify_args args) i
+    let outfd = get_fd Unix.stdout stdout_chan in
+    let errfd = get_fd Unix.stderr stderr_chan in
+    if echo_cmd then
+      debug "%s" (stringify_args args);
+    let pid = Unix.create_process app (Array.of_list args) Unix.stdin
+                outfd errfd in
+    Either (pid, app, stdout_chan, stderr_chan)
   with
-  | Executable_not_found tool -> 127
-  | Unix.Unix_error (errcode, _, _) when errcode = Unix.ENOENT -> 127
+  | Executable_not_found _ ->
+    Or 127
+  | Unix.Unix_error (errcode, _, _) when errcode = Unix.ENOENT ->
+    Or 127
+
+and do_teardown app outfd errfd exitstat =
+  may Unix.close outfd;
+  may Unix.close errfd;
+  match exitstat with
+  | Unix.WEXITED i ->
+    i
+  | Unix.WSIGNALED i ->
+    error (f_"external command ‘%s’ killed by signal %d") app i
+  | Unix.WSTOPPED i ->
+    error (f_"external command ‘%s’ stopped by signal %d") app i
 
 let shell_command ?(echo_cmd = true) cmd =
   if echo_cmd then
diff --git a/mllib/common_utils.mli b/mllib/common_utils.mli
index c088f8497..ee8c2e6da 100644
--- a/mllib/common_utils.mli
+++ b/mllib/common_utils.mli
@@ -374,7 +374,26 @@ val external_command : ?echo_cmd:bool -> string -> string list
     [echo_cmd] specifies whether to output the full command on verbose
     mode, and it's on by default. *)
 
-val run_command : ?echo_cmd:bool -> string list -> int
+val run_commands : ?echo_cmd:bool -> (string list * Unix.file_descr option * Unix.file_descr option) list -> int list
+(** Run external commands in parallel without using a shell,
+    and return a list with their exit codes.
+
+    The list of commands is composed as tuples:
+    - the first element is a list of command and its arguments
+    - the second element is an optional [Unix.file_descr] descriptor
+      for the stdout of the process; if not specified, [stdout] is
+      used
+    - the third element is an optional [Unix.file_descr] descriptor
+      for the stderr of the process; if not specified, [stderr] is
+      used
+
+    If any descriptor is specified, it is automatically closed at the
+    end of the execution of the command for which it was specified.
+
+    [echo_cmd] specifies whether output the full command on verbose
+    mode, and it's on by default. *)
+
+val run_command : ?echo_cmd:bool -> ?stdout_chan:Unix.file_descr -> ?stderr_chan:Unix.file_descr -> string list -> int
 (** Run an external command without using a shell, and return its exit code.
 
     [echo_cmd] specifies whether output the full command on verbose
diff --git a/mllib/common_utils_tests.ml b/mllib/common_utils_tests.ml
index aacc01e04..4c9f53fdf 100644
--- a/mllib/common_utils_tests.ml
+++ b/mllib/common_utils_tests.ml
@@ -26,6 +26,7 @@ let assert_equal_string = assert_equal ~printer:(fun x -> x)
 let assert_equal_int = assert_equal ~printer:(fun x -> string_of_int x)
 let assert_equal_int64 = assert_equal ~printer:(fun x -> Int64.to_string x)
 let assert_equal_stringlist = assert_equal ~printer:(fun x -> "(" ^ (String.escaped (String.concat "," x)) ^ ")")
+let assert_equal_intlist = assert_equal ~printer:(fun x -> "(" ^ (String.concat ";" (List.map string_of_int x)) ^ ")")
 
 let test_subdirectory ctx =
   assert_equal_string "" (subdirectory "/foo" "/foo");
@@ -131,6 +132,73 @@ let test_string_lines_split ctx =
   assert_equal_stringlist ["A\nB"; ""] (String.lines_split "A\\\nB\n");
   assert_equal_stringlist ["A\nB\n"] (String.lines_split "A\\\nB\\\n")
 
+(* Test Common_utils.run_command. *)
+let test_run_command ctx =
+  assert_equal_int 0 (run_command ["true"]);
+  begin
+    let tmpfile, chan = bracket_tmpfile ctx in
+    let res = run_command ["echo"; "this is a test"] ~stdout_chan:(Unix.descr_of_out_channel chan) in
+    assert_equal_int 0 res;
+    let content = read_whole_file tmpfile in
+    assert_equal_string "this is a test\n" content
+  end;
+  begin
+    let tmpfile, chan = bracket_tmpfile ctx in
+    let res = run_command ["ls"; "/this-directory-is-unlikely-to-exist"] ~stderr_chan:(Unix.descr_of_out_channel chan) in
+    assert_equal_int 2 res;
+    let content = read_whole_file tmpfile in
+    assert_bool "test_run_commands/not-existing/content" (String.length content > 0)
+  end;
+  ()
+
+(* Test Common_utils.run_commands. *)
+let test_run_commands ctx =
+  begin
+    let res = run_commands [] in
+    assert_equal_intlist [] res
+  end;
+  begin
+    let res = run_commands [(["true"], None, None)] in
+    assert_equal_intlist [0] res
+  end;
+  begin
+    let res = run_commands [(["true"], None, None); (["false"], None, None)] in
+    assert_equal_intlist [0; 1] res
+  end;
+  begin
+    let res = run_commands [(["this-command-does-not-really-exist"], None, None)] in
+    assert_equal_intlist [127] res
+  end;
+  begin
+    let tmpfile, chan = bracket_tmpfile ctx in
+    let res = run_commands [(["echo"; "this is a test"], Some (Unix.descr_of_out_channel chan), None)] in
+    assert_equal_intlist [0] res;
+    let content = read_whole_file tmpfile in
+    assert_equal_string "this is a test\n" content
+  end;
+  begin
+    let tmpfile, chan = bracket_tmpfile ctx in
+    let res = run_commands [(["ls"; "/this-directory-is-unlikely-to-exist"], None, Some (Unix.descr_of_out_channel chan))] in
+    assert_equal_intlist [2] res;
+    let content = read_whole_file tmpfile in
+    assert_bool "test_run_commands/not-existing/content" (String.length content > 0)
+  end;
+  begin
+    let tmpfile, chan = bracket_tmpfile ctx in
+    let res = run_commands [(["echo"; "this is a test"], Some (Unix.descr_of_out_channel chan), None); (["false"], None, None)] in
+    assert_equal_intlist [0; 1] res;
+    let content = read_whole_file tmpfile in
+    assert_equal_string "this is a test\n" content
+  end;
+  begin
+    let tmpfile, chan = bracket_tmpfile ctx in
+    let res = run_commands [(["this-command-does-not-really-exist"], None, None); (["echo"; "this is a test"], Some (Unix.descr_of_out_channel chan), None)] in
+    assert_equal_intlist [127; 0] res;
+    let content = read_whole_file tmpfile in
+    assert_equal_string "this is a test\n" content
+  end;
+  ()
+
 (* Suites declaration. *)
 let suite =
   "mllib Common_utils" >:::
@@ -143,6 +211,8 @@ let suite =
       "strings.is_suffix" >:: test_string_is_suffix;
       "strings.find" >:: test_string_find;
       "strings.lines_split" >:: test_string_lines_split;
+      "run_command" >:: test_run_command;
+      "run_commands" >:: test_run_commands;
     ]
 
 let () =