diff --git a/wasm/link_wast.ml b/wasm/link_wast.ml
new file mode 100644
index 000000000..4d46d95f0
--- /dev/null
+++ b/wasm/link_wast.ml
@@ -0,0 +1,82 @@
+type wasm_compilation_unit = string
+
+let tmp_dirname = "wasocaml"
+
+type tmp_file =
+  { name : string
+  ; filename : string
+  }
+
+let out_file (name, (wast : Wast.t)) =
+  let filename, oc =
+    Filename.open_temp_file (tmp_dirname ^ "/" ^ name) ".wast"
+  in
+  Format.printf "tmp_file: %s@." filename;
+  let ppf = Format.formatter_of_out_channel oc in
+  Misc.try_finally
+    ~always:(fun () ->
+      Format.fprintf ppf "@.";
+      close_out oc )
+    (fun () ->
+      Emit_wast.output_wast ppf wast.module_;
+      Format.fprintf ppf "@\n";
+      Emit_wast.output_wast ppf wast.register );
+  { name; filename }
+
+let emit_text = "--emit-text"
+let skip_export_conflicts = "--skip-export-conflicts"
+let options =
+  [ "--enable-multivalue"
+  ; "--enable-gc"
+  ; "--enable-reference-types"
+  ; "--enable-exception-handling"
+  ; "--enable-tail-call"
+  ]
+(* let wasm_merge = "wasm-merge" *)
+let wasm_merge = "/home/chambart/test/wasm/binaryen/bin/wasm-merge"
+
+let runtime =
+  [ (Wstate.exc_tag_module, Wstate.exc_tag_module)
+  ; (Wstate.runtime_module ^ "_binaryen", Wstate.runtime_module)
+  ; (Wstate.imports_module ^ "_binaryen", Wstate.imports_module)
+  ]
+
+let merge_files ~runtime_dir ~text files output =
+  let text = if text then [ emit_text ] else [] in
+  let command =
+    let runtime_files =
+      List.concat_map
+        (fun (file, name) -> [ Filename.concat runtime_dir (file ^ ".wast"); name ])
+        runtime
+    in
+    let ocaml_files =
+      List.concat_map (fun { name; filename } -> [ filename; name ]) files
+    in
+    Filename.quote_command wasm_merge
+      ( options @ [ skip_export_conflicts ] @ text @ runtime_files @ ocaml_files
+      @ [ "-o"; output ] )
+  in
+  Format.printf "%s@." command;
+  let code = Sys.command command in
+  if code <> 0 then begin Format.eprintf "wasm-merge failed@."
+    (* failwith "Wasm link error" *)
+  end
+
+let rec make_directory dir =
+  if Sys.file_exists dir then ()
+  else begin
+    make_directory (Filename.dirname dir);
+    Sys.mkdir dir 0o777
+  end
+
+let link (modules : (wasm_compilation_unit * Wast.t) list) ~output =
+  let output_wast = output ^ ".wast" in
+  let output_wasm = output ^ ".wasm" in
+  Format.eprintf "OUTPUT: %s@." output_wast;
+  let dirname = Filename.concat (Filename.get_temp_dir_name ()) tmp_dirname in
+  make_directory dirname;
+  (* Sys.mkdir dirname 0o700; *)
+  let tmp_modules = List.map out_file modules in
+  let runtime_dir = Config.standard_library in
+  merge_files ~runtime_dir ~text:true tmp_modules output_wast;
+  merge_files ~runtime_dir ~text:false tmp_modules output_wasm
diff --git a/wasm/link_wast.mli b/wasm/link_wast.mli
new file mode 100644
index 000000000..0f1afe0a5
--- /dev/null
+++ b/wasm/link_wast.mli
@@ -0,0 +1,4 @@
+
+type wasm_compilation_unit = string
+
+val link : (wasm_compilation_unit * Wast.t) list -> output:string -> unit