diff --git a/src/cmdliner.mli b/src/cmdliner.mli
index 43622e2..c6d179a 100644
--- a/src/cmdliner.mli
+++ b/src/cmdliner.mli
@@ -573,8 +573,10 @@ module Cmd : sig
     (** {1:info Environment variable information} *)
 
     [@@@alert "-deprecated"]
+
     type info = Term.env_info (* because of Arg. *)
     (** The type for environment variable information. *)
+
     [@@@alert "+deprecated"]
 
     val info : ?deprecated:string -> ?docs:string -> ?doc:string -> var -> info
@@ -799,11 +801,13 @@ module Arg : sig
   (** The type for converted argument printers. *)
 
   [@@@alert "-deprecated"] (* Need to be able to mention them ! *)
+
   type 'a conv = 'a parser * 'a printer
   (** The type for argument converters.
 
       {b Warning.} Do not use directly, use {!val-conv} or {!val-conv'}.
       This type will become abstract in the next major version of cmdliner. *)
+
   [@@@alert "+deprecated"] (* Need to be able to mention them ! *)
 
   val conv :
@@ -947,6 +951,15 @@ module Arg : sig
       {b Note.} Environment variable lookup is unsupported for
       for these arguments. *)
 
+  val alias : string list -> info -> bool t
+  (** [alias l i] is a [flag i] except the arguments [l] are also parsed as
+     if they appeared in place of the option. *)
+
+  val alias_opt : (string -> string list) -> info -> bool t
+  (** [alias l i] is a [flag i] except the arguments [l arg] are also parsed as
+     if they appeared in place of the option. [arg] is the possible argument
+     given on the command line *)
+
   val opt : ?vopt:'a -> 'a conv -> 'a -> info -> 'a t
   (** [opt vopt c v i] is an ['a] argument defined by the value of
       an optional argument that may appear {e at most} once on the command
diff --git a/src/cmdliner_arg.ml b/src/cmdliner_arg.ml
index 56d1fb6..f32a36d 100644
--- a/src/cmdliner_arg.ml
+++ b/src/cmdliner_arg.ml
@@ -96,6 +96,35 @@ let list_to_args f l =
   let add acc v = Cmdliner_info.Arg.Set.add (f v) acc in
   List.fold_left add Cmdliner_info.Arg.Set.empty l
 
+let alias_opt aliases a =
+  let a = Cmdliner_info.Arg.make_opt ~absent:Err ~kind:Opt a in
+  let aliases = (fun f -> function
+    | None -> Error (Cmdliner_msg.err_opt_value_missing f)
+    | Some o -> Ok (aliases o)) in
+  let a = Cmdliner_info.Arg.aliases ~aliases a in
+  if Cmdliner_info.Arg.is_pos a then invalid_arg err_not_opt else
+  let convert ei cl = match Cmdliner_cline.opt_arg cl a with
+  | [] -> try_env ei a Cmdliner_base.env_bool_parse ~absent:false
+  | [_, _, None] -> Ok true
+  | [_, f, Some v] -> Ok true
+  | (_, f, _) :: (_ ,g, _) :: _  -> err (Cmdliner_msg.err_opt_repeated f g)
+  in
+  arg_to_args a, convert
+
+let alias aliases a =
+  let aliases = (fun f -> function
+    | Some v -> Error (Cmdliner_msg.err_flag_value f v)
+    | None -> Ok aliases) in
+  let a = Cmdliner_info.Arg.aliases ~aliases a in
+  if Cmdliner_info.Arg.is_pos a then invalid_arg err_not_opt else
+  let convert ei cl = match Cmdliner_cline.opt_arg cl a with
+  | [] -> try_env ei a Cmdliner_base.env_bool_parse ~absent:false
+  | [_, _, None] -> Ok true
+  | [_, f, Some v] -> err (Cmdliner_msg.err_flag_value f v)
+  | (_, f, _) :: (_ ,g, _) :: _  -> err (Cmdliner_msg.err_opt_repeated f g)
+  in
+  arg_to_args a, convert
+
 let flag a =
   if Cmdliner_info.Arg.is_pos a then invalid_arg err_not_opt else
   let convert ei cl = match Cmdliner_cline.opt_arg cl a with
diff --git a/src/cmdliner_arg.mli b/src/cmdliner_arg.mli
index e3faa2f..4375b41 100644
--- a/src/cmdliner_arg.mli
+++ b/src/cmdliner_arg.mli
@@ -45,6 +45,8 @@ val flag : info -> bool t
 val flag_all : info -> bool list t
 val vflag : 'a -> ('a * info) list -> 'a t
 val vflag_all : 'a list -> ('a * info) list -> 'a list t
+val alias : string list -> info -> bool t
+val alias_opt : (string -> string list) -> info -> bool t
 val opt : ?vopt:'a -> 'a converter -> 'a -> info -> 'a t
 val opt_all : ?vopt:'a -> 'a converter -> 'a list -> info -> 'a list t
 
diff --git a/src/cmdliner_cline.ml b/src/cmdliner_cline.ml
index 5bff9d8..2b8108c 100644
--- a/src/cmdliner_cline.ml
+++ b/src/cmdliner_cline.ml
@@ -110,6 +110,11 @@ let parse_opt_args ~peek_opts optidx cl args =
               | v :: rest -> if is_opt v then None, args else Some v, rest
           in
           let arg = O ((k, name, value) :: opt_arg cl a) in
+          let errs,args =
+            match Cmdliner_info.Arg.alias a name value with
+            | Ok l -> errs,l@args
+            | Error err -> err::errs,args
+          in
           loop errs (k + 1) (Amap.add a arg cl) pargs args
       | `Not_found when peek_opts -> loop errs (k + 1) cl pargs args
       | `Not_found ->
diff --git a/src/cmdliner_info.ml b/src/cmdliner_info.ml
index d516fc1..87dec76 100644
--- a/src/cmdliner_info.ml
+++ b/src/cmdliner_info.ml
@@ -92,7 +92,10 @@ module Arg = struct
       pos : pos_kind; (* positional arg kind. *)
       opt_kind : opt_kind; (* optional arg kind. *)
       opt_names : string list; (* names (for opt args). *)
-      opt_all : bool; } (* repeatable (for opt args). *)
+      opt_all : bool; (* repeatable (for opt args). *)
+      opt_alias: string -> string option -> (string list, string) Result.t; (* [opt_alias arg value], [arg] is the name of the argument,
+        and [value] is the possible value *)
+    }
 
   let dumb_pos = pos ~rev:false ~start:(-1) ~len:None
 
@@ -108,7 +111,8 @@ module Arg = struct
     in
     { id = Cmdliner_base.uid (); deprecated; absent = Doc absent;
       env; doc; docv; docs; pos = dumb_pos; opt_kind = Flag; opt_names;
-      opt_all = false; }
+      opt_all = false;
+    opt_alias = fun _ _ -> Ok [] }
 
   let id a = a.id
   let deprecated a = a.deprecated
@@ -129,6 +133,7 @@ module Arg = struct
     | n :: ns -> if (String.length n) > 2 then n else find ns
     in
     find a.opt_names
+  let alias a = a.opt_alias
 
   let make_req a = { a with absent = Err }
   let make_all_opts a = { a with opt_all = true }
@@ -138,6 +143,7 @@ module Arg = struct
 
   let make_pos ~pos a = { a with pos }
   let make_pos_abs ~absent ~pos a = { a with absent; pos }
+  let aliases ~aliases a = { a with opt_alias = aliases }
 
   let is_opt a = a.opt_names <> []
   let is_pos a = a.opt_names = []
diff --git a/src/cmdliner_info.mli b/src/cmdliner_info.mli
index d82b03c..2b995a2 100644
--- a/src/cmdliner_info.mli
+++ b/src/cmdliner_info.mli
@@ -77,6 +77,7 @@ module Arg : sig
   val opt_name_sample : t -> string (* warning must be an opt arg *)
   val opt_kind : t -> opt_kind
   val pos_kind : t -> pos_kind
+  val alias : t -> string -> string option -> (string list, string) Result.t
 
   val make_req : t -> t
   val make_all_opts : t -> t
@@ -84,6 +85,7 @@ module Arg : sig
   val make_opt_all : absent:absence -> kind:opt_kind -> t -> t
   val make_pos : pos:pos_kind -> t -> t
   val make_pos_abs : absent:absence -> pos:pos_kind -> t -> t
+  val aliases : aliases:(string -> string option -> (string list, string) Result.t) -> t -> t
 
   val is_opt : t -> bool
   val is_pos : t -> bool
diff --git a/src/cmdliner_manpage.ml b/src/cmdliner_manpage.ml
index 46353d5..699564c 100644
--- a/src/cmdliner_manpage.ml
+++ b/src/cmdliner_manpage.ml
@@ -22,6 +22,7 @@ let s_name = "NAME"
 let s_synopsis = "SYNOPSIS"
 let s_description = "DESCRIPTION"
 let s_commands = "COMMANDS"
+let s_command_aliases = "COMMAND ALIASES"
 let s_arguments = "ARGUMENTS"
 let s_options = "OPTIONS"
 let s_common_options = "COMMON OPTIONS"