diff --git a/pkgs/development/ocaml-modules/atdgen/codec-runtime.nix b/pkgs/development/ocaml-modules/atdgen/codec-runtime.nix
index a2f3b32b7fcc..6dce840e914c 100644
--- a/pkgs/development/ocaml-modules/atdgen/codec-runtime.nix
+++ b/pkgs/development/ocaml-modules/atdgen/codec-runtime.nix
@@ -2,11 +2,11 @@
 
 buildDunePackage rec {
   pname = "atdgen-codec-runtime";
-  version = "2.9.1";
+  version = "2.10.0";
 
   src = fetchurl {
     url = "https://github.com/ahrefs/atd/releases/download/${version}/atdts-${version}.tbz";
-    sha256 = "sha256-OdwaUR0Ix0Oz8NDm36nIyvIRzF+r/pKgiej1fhcOmuQ=";
+    sha256 = "sha256-d9J0CaTp2sQbnKLp6mCDbGwYAIsioVer7ftaLSSFCZg=";
   };
 
   meta = {
diff --git a/pkgs/development/ocaml-modules/atdgen/runtime.nix b/pkgs/development/ocaml-modules/atdgen/runtime.nix
index 0fc98a1f66be..0006e8613c58 100644
--- a/pkgs/development/ocaml-modules/atdgen/runtime.nix
+++ b/pkgs/development/ocaml-modules/atdgen/runtime.nix
@@ -1,4 +1,4 @@
-{ buildDunePackage, atdgen-codec-runtime, biniou, camlp-streams, yojson }:
+{ buildDunePackage, atdgen-codec-runtime, biniou, yojson }:
 
 buildDunePackage rec {
   pname = "atdgen-runtime";
@@ -6,7 +6,7 @@ buildDunePackage rec {
 
   minimalOCamlVersion = "4.08";
 
-  propagatedBuildInputs = [ biniou camlp-streams yojson ];
+  propagatedBuildInputs = [ biniou yojson ];
 
   meta = atdgen-codec-runtime.meta // {
     description = "Runtime library for code generated by atdgen";
diff --git a/pkgs/development/ocaml-modules/elpi/atd_2_10.patch b/pkgs/development/ocaml-modules/elpi/atd_2_10.patch
new file mode 100644
index 000000000000..3f341a3fa4b4
--- /dev/null
+++ b/pkgs/development/ocaml-modules/elpi/atd_2_10.patch
@@ -0,0 +1,13 @@
+diff --git a/src/elpi_trace_elaborator.ml b/src/elpi_trace_elaborator.ml
+index ca13114d..093e7593 100644
+--- a/src/elpi_trace_elaborator.ml
++++ b/src/elpi_trace_elaborator.ml
+@@ -664,6 +664,6 @@ let main =
+ 
+   let cards = Trace.cards steps ~stack_frames ~aggregated_goal_success ~goal_text ~goal_attempts in
+ 
+-  let ob = Bi_outbuf.create_channel_writer stdout in
++  let ob = Buffer.create 17 in
+   write_trace ob cards;
+-  Bi_outbuf.flush_channel_writer ob
++  Buffer.output_buffer stdout ob
diff --git a/pkgs/development/ocaml-modules/elpi/default.nix b/pkgs/development/ocaml-modules/elpi/default.nix
index b9a81a6c9d9c..428e42682329 100644
--- a/pkgs/development/ocaml-modules/elpi/default.nix
+++ b/pkgs/development/ocaml-modules/elpi/default.nix
@@ -31,6 +31,9 @@ buildDunePackage rec {
   pname = "elpi";
   inherit (fetched) version src;
 
+  patches = lib.optional (versionAtLeast version "1.16" || version == "dev")
+    ./atd_2_10.patch;
+
   minimalOCamlVersion = "4.04";
 
   buildInputs = [ perl ncurses ]
diff --git a/pkgs/development/ocaml-modules/yojson/default.nix b/pkgs/development/ocaml-modules/yojson/default.nix
index 03b01c437766..38960dceb5e3 100644
--- a/pkgs/development/ocaml-modules/yojson/default.nix
+++ b/pkgs/development/ocaml-modules/yojson/default.nix
@@ -1,17 +1,16 @@
-{ lib, fetchurl, buildDunePackage, cppo, easy-format, biniou }:
+{ lib, fetchurl, buildDunePackage, cppo, seq }:
 
 buildDunePackage rec {
   pname = "yojson";
-  version = "1.7.0";
-  useDune2 = true;
+  version = "2.0.2";
 
   src = fetchurl {
     url = "https://github.com/ocaml-community/yojson/releases/download/${version}/yojson-${version}.tbz";
-    sha256 = "1iich6323npvvs8r50lkr4pxxqm9mf6w67cnid7jg1j1g5gwcvv5";
+    sha256 = "sha256-h2u284r3OoSilDij2jXkhXxgoUVWpgZSWxSMb9vlRhs=";
   };
 
   nativeBuildInputs = [ cppo ];
-  propagatedBuildInputs = [ easy-format biniou ];
+  propagatedBuildInputs = [ seq ];
 
   meta = with lib; {
     description = "An optimized parsing and printing library for the JSON format";
diff --git a/pkgs/development/tools/ocaml/merlin/4.x.nix b/pkgs/development/tools/ocaml/merlin/4.x.nix
index b5100afee984..e917a5a76da6 100644
--- a/pkgs/development/tools/ocaml/merlin/4.x.nix
+++ b/pkgs/development/tools/ocaml/merlin/4.x.nix
@@ -6,7 +6,7 @@
 , buildDunePackage
 , yojson
 , csexp
-, result
+, merlin-lib
 , dot-merlin-reader
 , jq
 , menhir
@@ -15,13 +15,12 @@
 }:
 
 let
-  merlinVersion = "4.5";
+  merlinVersion = "4.6";
 
   hashes = {
-    "4.5-411" = "sha256:05nz6y7r91rh0lj8b6xdv3s3yknmvjc7y60v17kszgqnr887bvpn";
-    "4.5-412" = "sha256:0i5c3rfzinmwdjya7gv94zyknsm32qx9dlg472xpfqivwvnnhf1z";
-    "4.5-413" = "sha256:1sphq9anfg1qzrvj7hdcqflj6cmc1qiyfkljhng9fxnnr0i7550s";
-    "4.5-414" = "sha256:13h588kwih05zd9p3p7q528q4zc0d1l983kkvbmkxgay5d17nn1i";
+    "4.6-412" = "sha256-isiurLeWminJQQR4oHpJPCzVk6cEmtQdX4+n3Pdka5c=";
+    "4.6-413" = "sha256-8903H4TE6F/v2Kw1XpcpdXEiLIdb9llYgt42zSR9kO4=";
+    "4.6-414" = "sha256-AuvXCjx32JQBY9vkxAd0pEjtFF6oTgrT1f9TJEEDk84=";
   };
 
   ocamlVersionShorthand = lib.concatStrings
@@ -49,12 +48,7 @@ buildDunePackage {
       dot_merlin_reader = "${dot-merlin-reader}/bin/dot-merlin-reader";
       dune = "${dune_2}/bin/dune";
     })
-  ] ++ lib.optional (lib.versionOlder ocaml.version "4.12")
-    # This fixes the test-suite on macOS
-    # See https://github.com/ocaml/merlin/pull/1399
-    # Fixed in 4.4 for OCaml ≥ 4.12
-    ./test.patch
-  ;
+  ];
 
   strictDeps = true;
 
@@ -65,8 +59,9 @@ buildDunePackage {
   buildInputs = [
     dot-merlin-reader
     yojson
-    csexp
-    result
+    (if lib.versionAtLeast version "4.6-414"
+     then merlin-lib
+     else csexp)
     menhirSdk
     menhirLib
   ];
diff --git a/pkgs/development/tools/ocaml/merlin/default.nix b/pkgs/development/tools/ocaml/merlin/default.nix
index 3db5d1377831..cff881d1c97e 100644
--- a/pkgs/development/tools/ocaml/merlin/default.nix
+++ b/pkgs/development/tools/ocaml/merlin/default.nix
@@ -3,16 +3,14 @@
 
 buildDunePackage rec {
   pname = "merlin";
-  version = "3.4.2";
+  version = "3.8.0";
 
   src = fetchurl {
-    url = "https://github.com/ocaml/merlin/releases/download/v${version}/merlin-v${version}.tbz";
-    sha256 = "e1b7b897b11119d92995c558530149fd07bd67a4aaf140f55f3c4ffb5e882a81";
+    url = "https://github.com/ocaml/merlin/releases/download/v${version}/merlin-${version}.tbz";
+    sha256 = "sha256-wmBGNwXL3BduF4o1sUXtAOUHJ4xmMvsWAxl/QdNj/28=";
   };
 
-  useDune2 = true;
-
-  minimumOCamlVersion = "4.02.3";
+  minimalOCamlVersion = "4.02.3";
 
   patches = [
     (substituteAll {
diff --git a/pkgs/development/tools/ocaml/merlin/dot-merlin-reader.nix b/pkgs/development/tools/ocaml/merlin/dot-merlin-reader.nix
index 894fe6f75ae9..e3fef3f4cc40 100644
--- a/pkgs/development/tools/ocaml/merlin/dot-merlin-reader.nix
+++ b/pkgs/development/tools/ocaml/merlin/dot-merlin-reader.nix
@@ -1,19 +1,15 @@
-{ lib, fetchurl, yojson, csexp, result, buildDunePackage }:
+{ lib, fetchurl, yojson, csexp, buildDunePackage, merlin-lib, merlin }:
 
 buildDunePackage rec {
   pname = "dot-merlin-reader";
-  version = "4.1";
 
-  useDune2 = true;
+  inherit (merlin) version src;
 
-  minimumOCamlVersion = "4.06";
+  minimalOCamlVersion = "4.06";
 
-  src = fetchurl {
-    url = "https://github.com/ocaml/merlin/releases/download/v${version}/dot-merlin-reader-v${version}.tbz";
-    sha256 = "14a36d6fb8646a5df4530420a7861722f1a4ee04753717947305e3676031e7cd";
-  };
-
-  buildInputs = [ yojson csexp result ];
+  buildInputs = if lib.versionAtLeast version "4.6-414"
+  then [ merlin-lib ]
+  else [ yojson csexp ];
 
   meta = with lib; {
     description = "Reads config files for merlin";
diff --git a/pkgs/development/tools/ocaml/merlin/lib.nix b/pkgs/development/tools/ocaml/merlin/lib.nix
new file mode 100644
index 000000000000..27c8035a5e3b
--- /dev/null
+++ b/pkgs/development/tools/ocaml/merlin/lib.nix
@@ -0,0 +1,14 @@
+{ lib, buildDunePackage, merlin, csexp }:
+
+buildDunePackage {
+  pname = "merlin-lib";
+  inherit (merlin) version src;
+
+  minimalOCamlVersion = "4.14";
+
+  propagatedBuildInputs = [ csexp ];
+
+  meta = merlin.meta // {
+    description = "Merlin’s libraries";
+  };
+}
diff --git a/pkgs/development/tools/ocaml/merlin/test.patch b/pkgs/development/tools/ocaml/merlin/test.patch
deleted file mode 100644
index 0101e825b967..000000000000
--- a/pkgs/development/tools/ocaml/merlin/test.patch
+++ /dev/null
@@ -1,19 +0,0 @@
-commit 282eed37f39ff216add8d53766fd59f3737eb87f
-Author: Vincent Laporte <Vincent.Laporte@gmail.com>
-Date:   Thu Nov 4 06:24:07 2021 +0100
-
-    Ignore dune stderr in tests
-
-diff --git a/tests/test-dirs/document/src-documentation.t/run.t b/tests/test-dirs/document/src-documentation.t/run.t
-index 2c9e1419..4f4c4327 100644
---- a/tests/test-dirs/document/src-documentation.t/run.t
-+++ b/tests/test-dirs/document/src-documentation.t/run.t
-@@ -42,7 +42,7 @@ documentation for the non-last defined value (in the same file) is show
-   > jq '.value'
-   " List reversal. "
- 
--  $ dune build --root=. ./doc.exe
-+  $ dune build --root=. ./doc.exe 2> /dev/null
-   $ cat >.merlin <<EOF
-   > B _build/default/.doc.eobjs/byte
-   > S .
diff --git a/pkgs/top-level/ocaml-packages.nix b/pkgs/top-level/ocaml-packages.nix
index 697459fb317f..a4302879c415 100644
--- a/pkgs/top-level/ocaml-packages.nix
+++ b/pkgs/top-level/ocaml-packages.nix
@@ -787,12 +787,14 @@ let
     menhirSdk = callPackage ../development/ocaml-modules/menhir/sdk.nix { };
 
     merlin =
-      if lib.versionAtLeast ocaml.version "4.11"
+      if lib.versionAtLeast ocaml.version "4.12"
       then callPackage ../development/tools/ocaml/merlin/4.x.nix { }
       else callPackage ../development/tools/ocaml/merlin { };
 
     merlin-extend = callPackage ../development/ocaml-modules/merlin-extend { };
 
+    merlin-lib = callPackage ../development/tools/ocaml/merlin/lib.nix { };
+
     dot-merlin-reader = callPackage ../development/tools/ocaml/merlin/dot-merlin-reader.nix { };
 
     metrics = callPackage ../development/ocaml-modules/metrics { };