diff --git a/doc/package-notes.xml b/doc/package-notes.xml
index dfdada3d28c2..169f70283e6d 100644
--- a/doc/package-notes.xml
+++ b/doc/package-notes.xml
@@ -883,6 +883,33 @@ citrix_receiver.override {
     On NixOS it can be installed using the following expression:
 <programlisting>{ pkgs, ... }: {
   fonts.fonts = with pkgs; [ noto-fonts-emoji ];
+}</programlisting>
+   </para>
+  </section>
+ </section>
+ <section xml:id="dlib">
+  <title>DLib</title>
+
+  <para>
+    <link xlink:href="http://dlib.net/">DLib</link> is a modern, C++-based toolkit which
+    provides several machine learning algorithms.
+  </para>
+
+  <section xml:id="compiling-without-avx-support">
+   <title>Compiling without AVX support</title>
+
+   <para>
+     Especially older CPUs don't support
+     <link xlink:href="https://en.wikipedia.org/wiki/Advanced_Vector_Extensions">AVX</link>
+     (<abbrev>Advanced Vector Extensions</abbrev>) instructions that are used by DLib to
+     optimize their algorithms.
+   </para>
+
+   <para>
+    On the affected hardware errors like <literal>Illegal instruction</literal> will occur.
+    In those cases AVX support needs to be disabled:
+<programlisting>self: super: {
+  dlib = super.dlib.override { avxSupport = false; };
 }</programlisting>
    </para>
   </section>
diff --git a/pkgs/development/libraries/dlib/default.nix b/pkgs/development/libraries/dlib/default.nix
index a88b3f1b9b68..67a56855bb79 100644
--- a/pkgs/development/libraries/dlib/default.nix
+++ b/pkgs/development/libraries/dlib/default.nix
@@ -1,5 +1,8 @@
 { stdenv, lib, fetchFromGitHub, cmake, pkgconfig, libpng, libjpeg
 , guiSupport ? false, libX11
+
+  # see http://dlib.net/compile.html
+, avxSupport ? true
 }:
 
 stdenv.mkDerivation rec {
@@ -17,6 +20,8 @@ stdenv.mkDerivation rec {
     rm -rf dlib/external
   '';
 
+  cmakeFlags = [ "-DUSE_AVX_INSTRUCTIONS=${if avxSupport then "yes" else "no"}" ];
+
   enableParallelBuilding = true;
   nativeBuildInputs = [ cmake pkgconfig ];
   buildInputs = [ libpng libjpeg ] ++ lib.optional guiSupport libX11;
diff --git a/pkgs/development/python-modules/dlib/default.nix b/pkgs/development/python-modules/dlib/default.nix
index 90e2c526789f..c200b6959b64 100644
--- a/pkgs/development/python-modules/dlib/default.nix
+++ b/pkgs/development/python-modules/dlib/default.nix
@@ -1,12 +1,17 @@
-{ buildPythonPackage, dlib, python, pytest }:
+{ buildPythonPackage, dlib, python, pytest, avxSupport ? true }:
 
 buildPythonPackage {
   inherit (dlib) name src nativeBuildInputs buildInputs meta;
 
+  # although AVX can be enabled, we never test with it. Some Hydra machines
+  # fail because of this, however their build results are probably used on hardware
+  # with AVX support.
   checkPhase = ''
     ${python.interpreter} nix_run_setup test --no USE_AVX_INSTRUCTIONS
   '';
 
+  setupPyBuildFlags = [ "--${if avxSupport then "yes" else "no"} USE_AVX_INSTRUCTIONS" ];
+
   patches = [ ./build-cores.patch ];
 
   checkInputs = [ pytest ];
diff --git a/pkgs/development/python-modules/face_recognition/default.nix b/pkgs/development/python-modules/face_recognition/default.nix
index b532c7d19f73..2856eeeab1b9 100644
--- a/pkgs/development/python-modules/face_recognition/default.nix
+++ b/pkgs/development/python-modules/face_recognition/default.nix
@@ -4,13 +4,13 @@
 
 buildPythonPackage rec {
   pname = "face_recognition";
-  version = "1.2.2";
+  version = "1.2.3";
 
   src = fetchFromGitHub {
     repo = pname;
     owner = "ageitgey";
-    rev = "v${version}";
-    sha256 = "17jnyr80j1p74gyvh1jabvwd3zsxvip2y7cjhh2g6gsjv2dpvrjv";
+    rev = "634db2e4309a365cee2503cb65d6f2e88f519d1e";
+    sha256 = "06zw5hq417d5yp17zynhxhb73074lx2qy64fqfzf711rw5vrn2mx";
   };
 
   postPatch = ''
@@ -19,6 +19,15 @@ buildPythonPackage rec {
 
   propagatedBuildInputs = [ pillow click dlib numpy face_recognition_models ];
 
+  # Our dlib is compiled with AVX instructions by default which breaks
+  # with "Illegal instruction" on some builders due to missing hardware features.
+  #
+  # As this makes the build fairly unreliable, it's better to skip the test and to ensure that
+  # the build is working and after each change to the package, manual testing should be done.
+  doCheck = false;
+
+  # Although tests are disabled by default, checkPhase still exists, so
+  # maintainers can check the package's functionality locally before modifying it.
   checkInputs = [ flake8 pytest glibcLocales ];
   checkPhase = ''
     LC_ALL="en_US.UTF-8" py.test