diff --git a/nixos/doc/manual/release-notes/rl-2003.xml b/nixos/doc/manual/release-notes/rl-2003.xml
index 41cf9d5eb15f..13981c0853d6 100644
--- a/nixos/doc/manual/release-notes/rl-2003.xml
+++ b/nixos/doc/manual/release-notes/rl-2003.xml
@@ -536,6 +536,9 @@ auth required pam_succeed_if.so uid >= 1000 quiet
        </listitem>
      </itemizedlist>
    </listitem>
+   <listitem>
+    <para>The LLVM versions 3.5, 3.9 and 4 (including the corresponding CLang versions) have been dropped.</para>
+   </listitem>
   </itemizedlist>
  </section>
 
diff --git a/pkgs/top-level/aliases.nix b/pkgs/top-level/aliases.nix
index 771e39f56350..c543af2405c3 100644
--- a/pkgs/top-level/aliases.nix
+++ b/pkgs/top-level/aliases.nix
@@ -540,4 +540,21 @@ mapAliases ({
   tor-browser-bundle = throw "tor-browser-bundle was removed because it was out of date and inadequately maintained. Please use tor-browser-bundle-bin instead. See #77452.";
   # added 2020-01-10
   tor-browser-unwrapped = throw "tor-browser-unwrapped was removed because it was out of date and inadequately maintained. Please use tor-browser-bundle-bin instead. See #77452.";
+
+    /* Cleanup before 20.09 */
+  llvm_4 = throw ''
+    The LLVM versions 3.5, 3.9 and 4.0 have been removed in NixOS 20.03
+    due to a lack of compatibility with glibc 2.30!
+  '';
+  llvm_39 = llvm_4;
+  llvm_35 = llvm_4;
+  lld_4 = llvm_4;
+
+  llvmPackages_4 = llvm_4;
+  llvmPackages_39 = llvm_4;
+  llvmPackages_35 = llvm_4;
+
+  clang_39 = llvm_4;
+  clang_35 = llvm_4;
+  clang_4 = llvm_4;
 })