diff --git a/ocaml-lsp-server/src/signature_help.ml b/ocaml-lsp-server/src/signature_help.ml
index 2c9d9e3a3..61f6c026c 100644
--- a/ocaml-lsp-server/src/signature_help.ml
+++ b/ocaml-lsp-server/src/signature_help.ml
@@ -10,178 +10,6 @@ open struct
   module Btype = Btype
 end
 
-type parameter_info =
-  { label : Typedtree.arg_label
-  ; param_start : int
-  ; param_end : int
-  ; argument : Typedtree.expression option
-  }
-
-type application_signature =
-  { function_name : string option
-  ; function_position : Msource.position
-  ; signature : string
-  ; parameters : parameter_info list
-  ; active_param : int option
-  }
-
-(* extract a properly parenthesized identifier from (expression_desc (Texp_ident
-   (Longident))) *)
-let extract_ident (exp_desc : Typedtree.expression_desc) =
-  let rec longident ppf : Longident.t -> unit = function
-    | Lident s -> Format.fprintf ppf "%s" (Misc_utils.parenthesize_name s)
-    | Ldot (p, s) ->
-      Format.fprintf ppf "%a.%s" longident p (Misc_utils.parenthesize_name s)
-    | Lapply (p1, p2) -> Format.fprintf ppf "%a(%a)" longident p1 longident p2
-  in
-  match exp_desc with
-  | Texp_ident (_, { txt = li; _ }, _, _, _) ->
-    let ppf, to_string = Format.to_string () in
-    longident ppf li;
-    Some (to_string ())
-  | _ -> None
-;;
-
-(* Type variables shared across arguments should all be printed with the same
-   name. [Printtyp.type_scheme] ensure that a name is unique within a given
-   type, but not across different invocations. [reset] followed by calls to
-   [mark_loops] and [type_sch] provide that *)
-let pp_type env ppf ty =
-  let module Printtyp = Type_utils.Printtyp in
-  Printtyp.wrap_printing_env env ~verbosity:(Lvl 0) (fun () ->
-    Printtyp.shared_type_scheme ppf ty)
-;;
-
-let rec type_is_arrow ty =
-  match Types.get_desc ty with
-  | Tarrow _ -> true
-  | Tlink ty -> type_is_arrow ty
-  | Tpoly (ty, _) -> type_is_arrow ty
-  | _ -> false
-;;
-
-(* surround function types in parentheses *)
-let pp_parameter_type env ppf ty =
-  if type_is_arrow ty
-  then Format.fprintf ppf "(%a)" (pp_type env) ty
-  else pp_type env ppf ty
-;;
-
-(* print parameter labels and types *)
-let pp_parameter env label ppf ty =
-  match (label : Typedtree.arg_label) with
-  | Nolabel -> pp_parameter_type env ppf ty
-  | Labelled l -> Format.fprintf ppf "%s:%a" l (pp_parameter_type env) ty
-  | Optional l ->
-    (* unwrap option for optional labels the same way as
-       [Raw_compat.labels_of_application] *)
-    let unwrap_option ty =
-      match Types.get_desc ty with
-      | Types.Tconstr (path, [ ty ], _) when Path.same path Predef.path_option -> ty
-      | _ -> ty
-    in
-    Format.fprintf ppf "?%s:%a" l (pp_parameter_type env) (unwrap_option ty)
-  | Position l -> Format.fprintf ppf "%s:[%%call_pos]" l
-;;
-
-(* record buffer offsets to be able to underline parameter types *)
-let print_parameter_offset ?arg:argument ppf buffer env label ty =
-  let param_start = Buffer.length buffer in
-  Format.fprintf ppf "%a%!" (pp_parameter env label) ty;
-  let param_end = Buffer.length buffer in
-  Format.pp_print_string ppf " -> ";
-  Format.pp_print_flush ppf ();
-  { label; param_start; param_end; argument }
-;;
-
-let separate_function_signature ~args (e : Typedtree.expression) =
-  Type_utils.Printtyp.reset ();
-  let buffer = Buffer.create 16 in
-  let ppf = Format.formatter_of_buffer buffer in
-  let rec separate ?(i = 0) ?(parameters = []) args ty =
-    match args, Types.get_desc ty with
-    | (_l, arg) :: args, Tarrow ((label, _, _), ty1, ty2, _) ->
-      let arg =
-        match arg with
-        | Typedtree.Arg (e, _sort) -> Some e
-        | Omitted _ -> None
-      in
-      let parameter = print_parameter_offset ppf buffer e.exp_env label ty1 ?arg in
-      separate args ty2 ~i:(succ i) ~parameters:(parameter :: parameters)
-    | [], Tarrow ((label, _, _), ty1, ty2, _) ->
-      let parameter = print_parameter_offset ppf buffer e.exp_env label ty1 in
-      separate args ty2 ~i:(succ i) ~parameters:(parameter :: parameters)
-    (* end of function type, print remaining type without recording offsets *)
-    | _ ->
-      Format.fprintf ppf "%a%!" (pp_type e.exp_env) ty;
-      { function_name = extract_ident e.exp_desc
-      ; function_position = `Offset e.exp_loc.loc_end.pos_cnum
-      ; signature = Buffer.contents buffer
-      ; parameters = List.rev parameters
-      ; active_param = None
-      }
-  in
-  separate args e.exp_type
-;;
-
-let active_parameter_by_arg ~arg params =
-  let find_by_arg = function
-    | { argument = Some a; _ } when a == arg -> true
-    | _ -> false
-  in
-  try Some (List.index params ~f:find_by_arg) with
-  | Not_found -> None
-;;
-
-let active_parameter_by_prefix ~prefix params =
-  let common = function
-    | Typedtree.Nolabel -> Some 0
-    | l when String.is_prefixed ~by:"~" prefix || String.is_prefixed ~by:"?" prefix ->
-      Some (String.common_prefix_len (Btype.prefixed_label_name l) prefix)
-    | _ -> None
-  in
-  let rec find_by_prefix ?(i = 0) ?longest_len ?longest_i = function
-    | [] -> longest_i
-    | p :: ps ->
-      (match common p.label, longest_len with
-       | Some common_len, Some longest_len when common_len > longest_len ->
-         find_by_prefix ps ~i:(succ i) ~longest_len:common_len ~longest_i:i
-       | Some common_len, None ->
-         find_by_prefix ps ~i:(succ i) ~longest_len:common_len ~longest_i:i
-       | _ -> find_by_prefix ps ~i:(succ i) ?longest_len ?longest_i)
-  in
-  find_by_prefix params
-;;
-
-let is_arrow t =
-  match Types.get_desc t with
-  | Tarrow _ -> true
-  | _ -> false
-;;
-
-let application_signature ~prefix = function
-  (* provide signature information for applied functions *)
-  | (_, Browse_raw.Expression arg)
-    :: (_, Expression { exp_desc = Texp_apply (({ exp_type; _ } as e), args, _, _, _); _ })
-    :: _
-    when is_arrow exp_type ->
-    let result = separate_function_signature e ~args in
-    let active_param = active_parameter_by_arg ~arg result.parameters in
-    let active_param =
-      match active_param with
-      | Some _ as ap -> ap
-      | None -> active_parameter_by_prefix ~prefix result.parameters
-    in
-    Some { result with active_param }
-  (* provide signature information directly after an unapplied function-type
-     value *)
-  | (_, Expression ({ exp_type; _ } as e)) :: _ when is_arrow exp_type ->
-    let result = separate_function_signature e ~args:[] in
-    let active_param = active_parameter_by_prefix ~prefix result.parameters in
-    Some { result with active_param }
-  | _ -> None
-;;
-
 let format_doc ~markdown ~doc =
   `MarkupContent
     (if markdown
@@ -195,11 +23,7 @@ let format_doc ~markdown ~doc =
      else { MarkupContent.value = doc; kind = MarkupKind.PlainText })
 ;;
 
-let run
-  ~log_info
-  (state : State.t)
-  { SignatureHelpParams.textDocument = { uri }; position; _ }
-  =
+let run (state : State.t) { SignatureHelpParams.textDocument = { uri }; position; _ } =
   let open Fiber.O in
   let doc =
     let store = state.store in
@@ -219,17 +43,15 @@ let run
     Fiber.return help
   | `Merlin merlin ->
     let* application_signature =
-      let* inside_comment =
-        Check_for_comments.position_in_comment ~log_info ~position ~merlin
-      in
+      let* inside_comment = Check_for_comments.position_in_comment ~position ~merlin in
       match inside_comment with
       | true -> Fiber.return None
       | false ->
-        Document.Merlin.with_pipeline_exn ~log_info merlin (fun pipeline ->
+        Document.Merlin.with_pipeline_exn ~name:"signature-help" merlin (fun pipeline ->
           let typer = Mpipeline.typer_result pipeline in
           let pos = Mpipeline.get_lexing_pos pipeline pos in
           let node = Mtyper.node_at typer pos in
-          application_signature node ~prefix)
+          Merlin_analysis.Signature_help.application_signature node ~prefix ~cursor:pos)
     in
     (match application_signature with
      | None ->
@@ -243,19 +65,21 @@ let run
        let offset = String.length prefix in
        let+ doc =
          Document.Merlin.doc_comment
-           ~log_info
+           ~name:"signature help-position"
            merlin
            application_signature.function_position
        in
        let info =
          let parameters =
-           List.map application_signature.parameters ~f:(fun (p : parameter_info) ->
-             let label = `Offset (offset + p.param_start, offset + p.param_end) in
-             ParameterInformation.create ~label ())
+           List.map
+             application_signature.parameters
+             ~f:(fun (p : Merlin_analysis.Signature_help.parameter_info) ->
+               let label = `Offset (offset + p.param_start, offset + p.param_end) in
+               ParameterInformation.create ~label ())
          in
          let documentation =
            let open Option.O in
-           let+ doc = doc in
+           let+ doc in
            let markdown =
              ClientCapabilities.markdown_support
                (State.client_capabilities state)
diff --git a/ocaml-lsp-server/src/signature_help.mli b/ocaml-lsp-server/src/signature_help.mli
index b51c457b6..0f9377c27 100644
--- a/ocaml-lsp-server/src/signature_help.mli
+++ b/ocaml-lsp-server/src/signature_help.mli
@@ -1,7 +1,3 @@
 open Import
 
-val run
-  :  log_info:Lsp_timing_logger.t
-  -> State.t
-  -> SignatureHelpParams.t
-  -> SignatureHelp.t Fiber.t
+val run : State.t -> SignatureHelpParams.t -> SignatureHelp.t Fiber.t