diff --git a/pkgs/development/compilers/llvm/15/default.nix b/pkgs/development/compilers/llvm/15/default.nix
index 0082ae8505e7..96c4c6e8aa4c 100644
--- a/pkgs/development/compilers/llvm/15/default.nix
+++ b/pkgs/development/compilers/llvm/15/default.nix
@@ -54,24 +54,10 @@ in
 let
   monorepoSrc' = monorepoSrc;
 in let
-  monorepoSrc = if monorepoSrc' != null then
-    monorepoSrc'
-  else let
-    sha256 = releaseInfo.original.sha256;
-    rev = if gitRelease != null then
-      gitRelease.rev
-    else
-      "llvmorg-${releaseInfo.version}";
-  in fetchFromGitHub {
-    owner = "llvm";
-    repo = "llvm-project";
-    inherit rev sha256;
-  };
-
   # Import releaseInfo separately to avoid infinite recursion
   inherit (import ../common/common-let.nix { inherit lib gitRelease officialRelease; }) releaseInfo;
   inherit (releaseInfo) release_version version;
-  inherit (import ../common/common-let.nix { inherit lib release_version gitRelease officialRelease; }) llvm_meta;
+  inherit (import ../common/common-let.nix { inherit lib fetchFromGitHub release_version gitRelease officialRelease monorepoSrc'; }) llvm_meta monorepoSrc;
 
   tools = lib.makeExtensible (tools: let
     callPackage = newScope (tools // { inherit stdenv cmake ninja libxml2 python3 release_version version monorepoSrc buildLlvmTools; });
diff --git a/pkgs/development/compilers/llvm/16/default.nix b/pkgs/development/compilers/llvm/16/default.nix
index 5213ebc37b47..d75e1a121a99 100644
--- a/pkgs/development/compilers/llvm/16/default.nix
+++ b/pkgs/development/compilers/llvm/16/default.nix
@@ -54,24 +54,10 @@ in
 let
   monorepoSrc' = monorepoSrc;
 in let
-  monorepoSrc = if monorepoSrc' != null then
-    monorepoSrc'
-  else let
-    sha256 = releaseInfo.original.sha256;
-    rev = if gitRelease != null then
-      gitRelease.rev
-    else
-      "llvmorg-${releaseInfo.version}";
-  in fetchFromGitHub {
-    owner = "llvm";
-    repo = "llvm-project";
-    inherit rev sha256;
-  };
-
   # Import releaseInfo separately to avoid infinite recursion
   inherit (import ../common/common-let.nix { inherit lib gitRelease officialRelease; }) releaseInfo;
   inherit (releaseInfo) release_version version;
-  inherit (import ../common/common-let.nix { inherit lib release_version gitRelease officialRelease; }) llvm_meta;
+  inherit (import ../common/common-let.nix { inherit lib fetchFromGitHub release_version gitRelease officialRelease monorepoSrc'; }) llvm_meta monorepoSrc;
 
   tools = lib.makeExtensible (tools: let
     callPackage = newScope (tools // { inherit stdenv cmake ninja libxml2 python3 release_version version monorepoSrc buildLlvmTools; });
diff --git a/pkgs/development/compilers/llvm/common/common-let.nix b/pkgs/development/compilers/llvm/common/common-let.nix
index d56063f1bc43..31360f5b98b9 100644
--- a/pkgs/development/compilers/llvm/common/common-let.nix
+++ b/pkgs/development/compilers/llvm/common/common-let.nix
@@ -1,10 +1,12 @@
 { lib
+, fetchFromGitHub ? null
 , release_version ? null
 , gitRelease ? null
 , officialRelease ? null
+, monorepoSrc' ? null
 }:
 
-{
+rec {
   llvm_meta = {
     license = lib.licenses.ncsa;
     maintainers = lib.teams.llvm.members;
@@ -37,4 +39,22 @@
           release_version;
     };
 
+  monorepoSrc =
+    if monorepoSrc' != null then
+      monorepoSrc'
+    else
+      let
+        sha256 = releaseInfo.original.sha256;
+        rev =
+          if gitRelease != null then
+            gitRelease.rev
+          else
+            "llvmorg-${releaseInfo.version}";
+      in
+      fetchFromGitHub {
+        owner = "llvm";
+        repo = "llvm-project";
+        inherit rev sha256;
+      };
+
 }
diff --git a/pkgs/development/compilers/llvm/git/default.nix b/pkgs/development/compilers/llvm/git/default.nix
index dc5ea642995c..2506d177a174 100644
--- a/pkgs/development/compilers/llvm/git/default.nix
+++ b/pkgs/development/compilers/llvm/git/default.nix
@@ -53,25 +53,10 @@ in
 let
   monorepoSrc' = monorepoSrc;
 in let
-  monorepoSrc = if monorepoSrc' != null then
-    monorepoSrc'
-  else let
-    sha256 = releaseInfo.original.sha256;
-    rev = if gitRelease != null then
-      gitRelease.rev
-    else
-      "llvmorg-${releaseInfo.version}";
-  in fetchFromGitHub {
-    owner = "llvm";
-    repo = "llvm-project";
-    inherit rev sha256;
-  };
-
-
   # Import releaseInfo separately to avoid infinite recursion
   inherit (import ../common/common-let.nix { inherit lib gitRelease officialRelease; }) releaseInfo;
   inherit (releaseInfo) release_version version;
-  inherit (import ../common/common-let.nix { inherit lib release_version gitRelease officialRelease; }) llvm_meta;
+  inherit (import ../common/common-let.nix { inherit lib fetchFromGitHub release_version gitRelease officialRelease monorepoSrc'; }) llvm_meta monorepoSrc;
 
   tools = lib.makeExtensible (tools: let
     callPackage = newScope (tools // { inherit stdenv cmake ninja libxml2 python3 release_version version monorepoSrc buildLlvmTools; });