diff --git a/pkgs/development/haskell-modules/cabal2nix-unstable.nix b/pkgs/development/haskell-modules/cabal2nix-unstable.nix
index 168e1f885c7d1..dbb99b7c62c78 100644
--- a/pkgs/development/haskell-modules/cabal2nix-unstable.nix
+++ b/pkgs/development/haskell-modules/cabal2nix-unstable.nix
@@ -35,10 +35,10 @@
 }:
 mkDerivation {
   pname = "cabal2nix";
-  version = "unstable-2025-09-06";
+  version = "unstable-2025-09-09";
   src = fetchzip {
-    url = "https://github.com/NixOS/cabal2nix/archive/fe1b21c9fb01f3f8a9028744499f20b7799cad38.tar.gz";
-    sha256 = "0g9pa8914mdnbbhy3far689xckfblavwv0ylmzi0h4p7v8alrjx7";
+    url = "https://github.com/NixOS/cabal2nix/archive/987474e0b0ed1c6b0e3fd0d07313f6996ec98b7e.tar.gz";
+    sha256 = "0nixn8incqypsfyfclj40p8bdx2yn4783kzwpqfp19ql2sbc57dc";
   };
   postUnpack = "sourceRoot+=/cabal2nix; echo source root reset to $sourceRoot";
   isLibrary = true;
diff --git a/pkgs/development/haskell-modules/configuration-ghc-9.0.x.nix b/pkgs/development/haskell-modules/configuration-ghc-9.0.x.nix
index 549523c2ff66e..3cd9002c3a028 100644
--- a/pkgs/development/haskell-modules/configuration-ghc-9.0.x.nix
+++ b/pkgs/development/haskell-modules/configuration-ghc-9.0.x.nix
@@ -13,8 +13,6 @@ in
 
 self: super: {
 
-  llvmPackages = pkgs.lib.dontRecurseIntoAttrs self.ghc.llvmPackages;
-
   # Disable GHC 9.0.x core libraries.
   array = null;
   base = null;
diff --git a/pkgs/development/haskell-modules/configuration-ghc-9.10.x.nix b/pkgs/development/haskell-modules/configuration-ghc-9.10.x.nix
index 40351fcd3635a..fbac3690a708d 100644
--- a/pkgs/development/haskell-modules/configuration-ghc-9.10.x.nix
+++ b/pkgs/development/haskell-modules/configuration-ghc-9.10.x.nix
@@ -16,8 +16,6 @@ let
 in
 
 {
-  llvmPackages = lib.dontRecurseIntoAttrs self.ghc.llvmPackages;
-
   # Disable GHC core libraries
   array = null;
   base = null;
diff --git a/pkgs/development/haskell-modules/configuration-ghc-9.12.x.nix b/pkgs/development/haskell-modules/configuration-ghc-9.12.x.nix
index 63162d068237b..79afa7b31ccb2 100644
--- a/pkgs/development/haskell-modules/configuration-ghc-9.12.x.nix
+++ b/pkgs/development/haskell-modules/configuration-ghc-9.12.x.nix
@@ -16,8 +16,6 @@ in
 with haskellLib;
 
 {
-  llvmPackages = lib.dontRecurseIntoAttrs self.ghc.llvmPackages;
-
   # Disable GHC core libraries
   array = null;
   base = null;
diff --git a/pkgs/development/haskell-modules/configuration-ghc-9.14.x.nix b/pkgs/development/haskell-modules/configuration-ghc-9.14.x.nix
index 2e743b996f6c9..555870017bcf2 100644
--- a/pkgs/development/haskell-modules/configuration-ghc-9.14.x.nix
+++ b/pkgs/development/haskell-modules/configuration-ghc-9.14.x.nix
@@ -6,8 +6,6 @@ let
 in
 
 self: super: {
-  llvmPackages = lib.dontRecurseIntoAttrs self.ghc.llvmPackages;
-
   # Disable GHC core libraries
   array = null;
   base = null;
diff --git a/pkgs/development/haskell-modules/configuration-ghc-9.2.x.nix b/pkgs/development/haskell-modules/configuration-ghc-9.2.x.nix
index cd67a884e853c..10e5d2bd55d9b 100644
--- a/pkgs/development/haskell-modules/configuration-ghc-9.2.x.nix
+++ b/pkgs/development/haskell-modules/configuration-ghc-9.2.x.nix
@@ -13,8 +13,6 @@ in
 
 self: super: {
 
-  llvmPackages = pkgs.lib.dontRecurseIntoAttrs self.ghc.llvmPackages;
-
   # Disable GHC 9.2.x core libraries.
   array = null;
   base = null;
diff --git a/pkgs/development/haskell-modules/configuration-ghc-9.4.x.nix b/pkgs/development/haskell-modules/configuration-ghc-9.4.x.nix
index 4a1afd49fcb1b..924f7c1309f80 100644
--- a/pkgs/development/haskell-modules/configuration-ghc-9.4.x.nix
+++ b/pkgs/development/haskell-modules/configuration-ghc-9.4.x.nix
@@ -6,8 +6,6 @@ in
 
 with haskellLib;
 self: super: {
-  llvmPackages = lib.dontRecurseIntoAttrs self.ghc.llvmPackages;
-
   # Disable GHC core libraries.
   array = null;
   base = null;
diff --git a/pkgs/development/haskell-modules/configuration-ghc-9.6.x.nix b/pkgs/development/haskell-modules/configuration-ghc-9.6.x.nix
index 60214323e8392..bfc688281f227 100644
--- a/pkgs/development/haskell-modules/configuration-ghc-9.6.x.nix
+++ b/pkgs/development/haskell-modules/configuration-ghc-9.6.x.nix
@@ -16,8 +16,6 @@ let
 in
 
 {
-  llvmPackages = lib.dontRecurseIntoAttrs self.ghc.llvmPackages;
-
   # Disable GHC core libraries
   array = null;
   base = null;
diff --git a/pkgs/development/haskell-modules/configuration-ghc-9.8.x.nix b/pkgs/development/haskell-modules/configuration-ghc-9.8.x.nix
index f56b3108ba517..e70da8a3e6882 100644
--- a/pkgs/development/haskell-modules/configuration-ghc-9.8.x.nix
+++ b/pkgs/development/haskell-modules/configuration-ghc-9.8.x.nix
@@ -18,8 +18,6 @@ in
 
 {
 
-  llvmPackages = pkgs.lib.dontRecurseIntoAttrs self.ghc.llvmPackages;
-
   # Disable GHC core libraries.
   array = null;
   base = null;
diff --git a/pkgs/development/haskell-modules/configuration-nix.nix b/pkgs/development/haskell-modules/configuration-nix.nix
index d08240cacf564..88fe314bdffc3 100644
--- a/pkgs/development/haskell-modules/configuration-nix.nix
+++ b/pkgs/development/haskell-modules/configuration-nix.nix
@@ -523,8 +523,22 @@ builtins.intersectAttrs super {
       )
     );
 
-  # Needs help finding LLVM.
-  spaceprobe = addBuildTool self.buildHaskellPackages.llvmPackages.llvm super.spaceprobe;
+  # Forces the LLVM backend; upstream signalled intent to remove this
+  # in 2017: <https://github.com/SeanRBurton/spaceprobe/issues/1>.
+  spaceprobe = overrideCabal (drv: {
+    postPatch = ''
+      substituteInPlace spaceprobe.cabal \
+        --replace-fail '-fllvm ' ""
+    '';
+  }) super.spaceprobe;
+
+  # Forces the LLVM backend.
+  GlomeVec = overrideCabal (drv: {
+    postPatch = ''
+      substituteInPlace GlomeVec.cabal \
+        --replace-fail '-fllvm ' ""
+    '';
+  }) super.GlomeVec;
 
   # Tries to run GUI in tests
   leksah = dontCheck (
diff --git a/pkgs/development/haskell-modules/hackage-packages.nix b/pkgs/development/haskell-modules/hackage-packages.nix
index 85eea82315fde..45910e661c6d8 100644
--- a/pkgs/development/haskell-modules/hackage-packages.nix
+++ b/pkgs/development/haskell-modules/hackage-packages.nix
@@ -16266,7 +16266,6 @@ self: {
       mkDerivation,
       array,
       base,
-      llvm,
     }:
     mkDerivation {
       pname = "GlomeVec";
@@ -16276,11 +16275,10 @@ self: {
         array
         base
       ];
-      libraryPkgconfigDepends = [ llvm ];
       description = "Simple 3D vector library";
       license = "GPL";
     }
-  ) { inherit (self.llvmPackages) llvm; };
+  ) { };
 
   "GlomeView" = callPackage (
     {
@@ -27647,9 +27645,9 @@ self: {
           base,
           bytestring,
           c2hs,
-          clang,
           filepath,
           hashable,
+          libclang,
           mtl,
           ncurses,
           resourcet,
@@ -27676,7 +27674,7 @@ self: {
             transformers-base
             vector
           ];
-          librarySystemDepends = [ clang ];
+          librarySystemDepends = [ libclang ];
           libraryPkgconfigDepends = [ ncurses ];
           libraryToolDepends = [ c2hs ];
           description = "Haskell bindings for libclang (a C++ parsing library)";
@@ -27686,7 +27684,7 @@ self: {
         }
       )
       {
-        inherit (self.llvmPackages) clang;
+        inherit (pkgs) libclang;
         inherit (pkgs) ncurses;
       };
 
@@ -141306,11 +141304,11 @@ self: {
       base,
       bytestring,
       Cabal,
-      clang,
       containers,
       contravariant,
       inline-c,
       lens,
+      libclang,
       microlens,
       microlens-contra,
       process,
@@ -141344,7 +141342,7 @@ self: {
         template-haskell
         vector
       ];
-      librarySystemDepends = [ clang ];
+      librarySystemDepends = [ libclang ];
       testHaskellDepends = [
         base
         bytestring
@@ -141355,7 +141353,7 @@ self: {
       hydraPlatforms = lib.platforms.none;
       broken = true;
     }
-  ) { inherit (self.llvmPackages) clang; };
+  ) { inherit (pkgs) libclang; };
 
   "clanki" = callPackage (
     {
@@ -267231,7 +267229,7 @@ self: {
       haskell-gi-overloading,
       text,
       transformers,
-      vte_291,
+      vte,
     }:
     mkDerivation {
       pname = "gi-vte";
@@ -267270,12 +267268,12 @@ self: {
         text
         transformers
       ];
-      libraryPkgconfigDepends = [ vte_291 ];
+      libraryPkgconfigDepends = [ vte ];
       description = "Vte bindings";
       license = lib.licenses.lgpl21Only;
       badPlatforms = lib.platforms.darwin;
     }
-  ) { vte_291 = pkgs.vte; };
+  ) { inherit (pkgs) vte; };
 
   "gi-webkit" = callPackage (
     {
@@ -664371,7 +664369,7 @@ self: {
           text,
           transformers,
           unordered-containers,
-          vte_291,
+          vte,
           xml-conduit,
           xml-html-qq,
           yaml,
@@ -664421,7 +664419,7 @@ self: {
           libraryPkgconfigDepends = [
             gtk3
             pcre2
-            vte_291
+            vte
           ];
           executableHaskellDepends = [ base ];
           testHaskellDepends = [
@@ -664441,7 +664439,7 @@ self: {
       {
         inherit (pkgs) gtk3;
         inherit (pkgs) pcre2;
-        vte_291 = pkgs.vte;
+        inherit (pkgs) vte;
       };
 
   "termplot" = callPackage (
diff --git a/pkgs/development/haskell-modules/make-package-set.nix b/pkgs/development/haskell-modules/make-package-set.nix
index 44dc232789638..d53c092ed0224 100644
--- a/pkgs/development/haskell-modules/make-package-set.nix
+++ b/pkgs/development/haskell-modules/make-package-set.nix
@@ -734,6 +734,6 @@ package-set { inherit pkgs lib callPackage; } self
   */
   forceLlvmCodegenBackend = overrideCabal (drv: {
     configureFlags = drv.configureFlags or [ ] ++ [ "--ghc-option=-fllvm" ];
-    buildTools = drv.buildTools or [ ] ++ [ self.llvmPackages.llvm ];
+    buildTools = drv.buildTools or [ ] ++ [ self.ghc.llvmPackages.llvm ];
   });
 }
diff --git a/pkgs/development/haskell-modules/with-packages-wrapper.nix b/pkgs/development/haskell-modules/with-packages-wrapper.nix
index b683febeaf6c9..0df9ec093ef7e 100644
--- a/pkgs/development/haskell-modules/with-packages-wrapper.nix
+++ b/pkgs/development/haskell-modules/with-packages-wrapper.nix
@@ -44,7 +44,7 @@ selectPackages:
 #   fi
 
 let
-  inherit (haskellPackages) llvmPackages ghc;
+  inherit (haskellPackages) ghc;
 
   hoogleWithPackages' = if withHoogle then hoogleWithPackages selectPackages else null;
 
@@ -71,7 +71,7 @@ let
   # CLang is needed on Darwin for -fllvm to work:
   # https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/codegens.html#llvm-code-generator-fllvm
   llvm = lib.makeBinPath (
-    [ llvmPackages.llvm ] ++ lib.optional stdenv.targetPlatform.isDarwin llvmPackages.clang
+    [ ghc.llvmPackages.llvm ] ++ lib.optional stdenv.targetPlatform.isDarwin ghc.llvmPackages.clang
   );
 in