diff --git a/.github/workflows/eval.yml b/.github/workflows/eval.yml
index a7c3a94a67880..14cbfd02b2262 100644
--- a/.github/workflows/eval.yml
+++ b/.github/workflows/eval.yml
@@ -6,12 +6,12 @@ permissions:
   contents: read
 
 jobs:
-  tests:
-    name: eval-check
+  attrs:
+    name: Attrs
     runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        system: [x86_64-linux, aarch64-linux, aarch64-darwin, x86_64-darwin]
+    outputs:
+      systems: ${{ steps.systems.outputs.systems }}
+      mergedSha: ${{ steps.merged.outputs.mergedSha }}
     steps:
       # Important: Because of `pull_request_target`, this doesn't check out the PR,
       # but rather the base branch of the PR, which is needed so we don't run untrusted code
@@ -20,12 +20,13 @@ jobs:
           path: base
           sparse-checkout: ci
       - name: Resolving the merge commit
+        id: merged
         env:
           GH_TOKEN: ${{ github.token }}
         run: |
           if mergedSha=$(base/ci/get-merge-commit.sh ${{ github.repository }} ${{ github.event.number }}); then
             echo "Checking the merge commit $mergedSha"
-            echo "mergedSha=$mergedSha" >> "$GITHUB_ENV"
+            echo "mergedSha=$mergedSha" >> "$GITHUB_OUTPUT"
           else
             # Skipping so that no notifications are sent
             echo "Skipping the rest..."
@@ -33,13 +34,52 @@ jobs:
           rm -rf base
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         # Add this to _all_ subsequent steps to skip them
-        if: env.mergedSha
+        if: outputs.merged.mergedSha
         with:
           ref: ${{ env.mergedSha }}
+          path: nixpkgs
+
+      - uses: cachix/install-nix-action@08dcb3a5e62fa31e2da3d490afc4176ef55ecd72 # v30
+        if: outputs.merged.mergedSha
+
+      - id: systems
+        if: outputs.merged.mergedSha
+        run: |
+          nix-build nixpkgs/ci -A eval.evalPlan
+          echo "systems=$(<result/systems.json)" > "GITHUB_OUTPUT"
+
+      - uses: actions/upload-artifact@b4b15b8c7c6ac21ea08fcf65892d2ee8f75cf882 v4.4.3
+        if: outputs.merged.mergedSha
+        with:
+          name: eval-plan
+          path: result/systems
+
+  eval:
+    name: Eval
+    runs-on: ubuntu-latest
+    needs: attrs
+    if: needs.attrs.outputs.mergedSha
+    strategy:
+      matrix:
+        system: ${{ fromJSON(needs.attrs.outputs.systems) }}
+    steps:
+      - uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
+        with:
+          name: eval-plan
+          path: systems
+
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        with:
+          ref: ${{ needs.attrs.outputs.mergedSha }}
+          path: nixpkgs
 
       - uses: cachix/install-nix-action@08dcb3a5e62fa31e2da3d490afc4176ef55ecd72 # v30
-        if: env.mergedSha
 
       - name: Check eval
-        if: env.mergedSha
-        run: ./ci/eval-nixpkgs.sh --system "${{ matrix.system }}"
+        run: nix-build nixpkgs/ci -A eval.singleJob --arg jobDir systems/${{ matrix.system }}
+
+      - uses: actions/upload-artifact@b4b15b8c7c6ac21ea08fcf65892d2ee8f75cf882 v4.4.3
+        if: outputs.merged.mergedSha
+        with:
+          name: result-${ matrix.system }}
+          path: result/paths
diff --git a/ci/default.nix b/ci/default.nix
index 02b2e948d17b8..f5a6cf7d3dd0e 100644
--- a/ci/default.nix
+++ b/ci/default.nix
@@ -26,4 +26,5 @@ in
   inherit pkgs;
   requestReviews = pkgs.callPackage ./request-reviews { };
   codeownersValidator = pkgs.callPackage ./codeowners-validator { };
+  eval = pkgs.callPackage ./eval { };
 }
diff --git a/ci/eval-nixpkgs.sh b/ci/eval-nixpkgs.sh
deleted file mode 100755
index ca1a22a99ac87..0000000000000
--- a/ci/eval-nixpkgs.sh
+++ /dev/null
@@ -1,89 +0,0 @@
-#!/usr/bin/env nix-shell
-#!nix-shell -i bash -p coreutils moreutils -I nixpkgs=channel:nixpkgs-unstable
-
-set -euxo pipefail
-
-SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" &>/dev/null && pwd)"
-NIXPKGS_PATH="$(readlink -f "$SCRIPT_DIR"/..)"
-
-system="x86_64-linux"
-quick_test=0
-CORES=$(nproc)
-
-parseArgs() {
-    while [[ $# -gt 0 ]]; do
-        arg=$1
-        shift
-        case "$arg" in
-        --system)
-            system=$1
-            shift 1
-            ;;
-        --cores)
-            CORES=$1
-            shift 1
-            ;;
-        --quick-test)
-            quick_test=1
-            ;;
-        *)
-            echo "Unknown argument: $arg"
-            exit 1
-            ;;
-        esac
-    done
-}
-
-main() {
-    parseArgs "$@"
-    tmpdir=$(mktemp -d)
-    trap 'rm -rf "$tmpdir"' EXIT
-
-    nix-instantiate --eval --strict --json --arg enableWarnings false "$NIXPKGS_PATH"/pkgs/top-level/release-attrpaths-superset.nix -A paths >"$tmpdir/paths.json"
-
-    # Originally @amjoseph: note that the number of processes spawned is four times
-    # the number of cores -- this helps in two ways:
-    # 1. Keeping cores busy while I/O operations are in flight
-    # 2. Since the amount of time needed for the jobs is *not* balanced
-    # this minimizes the "tail latency" for the very last job to finish
-    # (on one core) by making the job size smaller.
-    local num_chunks=$((4 * CORES))
-    local seq_end=$((num_chunks - 1))
-    if [[ $quick_test -eq 1 ]]; then
-        seq_end=0
-    fi
-
-    (
-        set +e
-        seq 0 $seq_end | xargs -P "$CORES" -I {} nix-env -qaP --no-name --out-path --arg checkMeta true --arg includeBroken true \
-            --arg systems "[\"$system\"]" \
-            -f "$NIXPKGS_PATH"/ci/parallel.nix --arg attrPathFile "$tmpdir"/paths.json \
-            --arg numChunks "$num_chunks" --show-trace --arg myChunk {} >"$tmpdir/paths"
-        echo $? >"$tmpdir/exit-code"
-    ) &
-    pid=$!
-    while kill -0 "$pid"; do
-        free -g >&2
-        sleep 20
-    done
-
-    # Extract derivation outputs for each attribute into a JSON object
-    # i.e. { "attr1": { "out": "/nix/store/...", "dev": "/nix/store/..." }, ... }
-    jq --raw-input --slurp '
-    split("\n") |
-    map(select(. != "") | split(" ") | map(select(. != ""))) |
-    map(
-        {
-            key: .[0],
-            value: .[1] | split(";") | map(split("=") |
-               if length == 1 then
-                   { key: "out", value: .[0] }
-               else
-                   { key: .[0], value: .[1] }
-               end) | from_entries}
-    ) | from_entries
-    ' "$tmpdir/paths"
-    exit "$(cat "$tmpdir/exit-code")"
-}
-
-main "$@"
diff --git a/ci/eval/default.nix b/ci/eval/default.nix
new file mode 100644
index 0000000000000..c8c32af198f65
--- /dev/null
+++ b/ci/eval/default.nix
@@ -0,0 +1,213 @@
+{
+  lib,
+  runCommand,
+  writeShellScript,
+  time,
+  procps,
+  nix,
+  jq,
+}:
+
+# Use the GitHub Actions cache to cache /nix/store
+# Although can't really merge..
+# Use artifacts and pass files manually, also doesn't have to repeat eval then
+let
+  nixpkgs = with lib.fileset; toSource {
+    root = ../..;
+    fileset = unions (map (lib.path.append ../..) [
+      "default.nix"
+      "doc"
+      "lib"
+      "maintainers"
+      "nixos"
+      "ci"
+      "pkgs"
+      ".version"
+    ]);
+  };
+
+  attrpathsSuperset =
+    runCommand "attrpaths-superset.json" {
+      src = nixpkgs;
+      nativeBuildInputs = [
+        nix
+      ];
+    }
+    ''
+      export NIX_STATE_DIR=$(mktemp -d)
+      mkdir $out
+      nix-instantiate --eval --strict --json $src/pkgs/top-level/release-attrpaths-superset.nix -A paths > $out/paths.json
+    '';
+
+  # Takes a path to an attrpathsSuperset result and computes the result of evaluating it entirely
+  evalPlan =
+    {
+      # null means as many cores as your machine has
+      cores ? null,
+      # How many attributes to be evaluating at any single time.
+      # This effectively limits the maximum memory usage.
+      # Decrease this if too much memory is used
+      simultaneousAttrsPerSystem ? 100000,
+      checkMeta ? true,
+      includeBroken ? true,
+      # TODO
+      quickTest ? false,
+    }:
+    runCommand "eval-plan" {
+      nativeBuildInputs = [
+        jq
+      ];
+      env.cores = toString cores;
+      supportedSystems = builtins.toJSON (import ../supportedSystems.nix);
+      passAsFile = [ "supportedSystems" ];
+    } ''
+      if [[ -z "$cores" ]]; then
+        cores=$(nproc)
+      fi
+      echo "Cores: $cores"
+      num_attrs=$(jq length "${attrpathsSuperset}/paths.json")
+      echo "Attribute count: $num_attrs"
+      chunk_size=$(( ${toString simultaneousAttrsPerSystem} / cores ))
+      echo "Chunk size: $chunk_size"
+      # Same as `num_attrs / chunk_size` but rounded up
+      num_chunks=$(( (num_attrs - 1) / chunk_size + 1 ))
+      echo "Chunk count: $num_chunks"
+
+      mkdir -p $out/systems
+      mv "$supportedSystemsPath" $out/systems.json
+      echo "Systems: $(<$out/systems.json)"
+      for system in $(jq -r '.[]' "$out/systems.json"); do
+        mkdir -p "$out/systems/$system/chunks"
+        printf "%s" "$cores" > "$out/systems/$system/cores"
+        for chunk in $(seq -w 0 "$(( num_chunks - 1 ))"); do
+          jq '{
+              paths: .[($chunk * $chunk_size):(($chunk + 1) * $chunk_size)],
+              systems: [ $system ],
+              checkMeta: $checkMeta,
+              includeBroken: $includeBroken
+            }' \
+            --argjson chunk "$chunk" \
+            --argjson chunk_size "$chunk_size" \
+            --arg system "$system" \
+            --argjson checkMeta "${lib.boolToString checkMeta}" \
+            --argjson includeBroken "${lib.boolToString includeBroken}" \
+            ${attrpathsSuperset}/paths.json \
+            > "$out/systems/$system/chunks/$chunk.json"
+        done
+      done
+    '';
+
+
+  singleSystem =
+    let
+      singleChunk = writeShellScript "chunk" ''
+        set -euo pipefail
+        chunkFile=$1
+        outputDir=$2
+
+        nix-env -f "${nixpkgs}/ci/eval/parallel.nix" \
+          --query --available \
+          --no-name --attr-path --out-path \
+          --show-trace \
+          --arg chunkFile "$chunkFile" > "$outputDir/$(basename "$chunkFile")"
+      '';
+    in
+    {
+      systemDir,
+    }:
+    runCommand "nixpkgs-eval-system-${baseNameOf systemDir}" {
+      nativeBuildInputs = [
+        nix
+        time
+        procps
+      ];
+    } ''
+      export NIX_STATE_DIR=$(mktemp -d)
+      nix-store --init
+
+      cores=$(<${systemDir}/cores)
+      chunkOutputDir=$(mktemp -d)
+
+      (
+        while true; do
+          free -g
+          sleep 20
+        done
+      ) &
+
+      find ${systemDir}/chunks -name '*.json' -print0 |
+        command time -v xargs -0 -t -I{} -P"$cores" \
+        ${singleChunk} {} "$chunkOutputDir"
+
+      cat "$chunkOutputDir"/* > $out/paths
+    '';
+
+  combine =
+    {
+
+    }: null;
+
+    #  mkdir $out
+    #  for system in ${lib.escapeShellArgs (import ../supportedSystems.nix)}; do
+
+    #  done
+
+    #'';
+
+  # Files of the form
+  # $out/<matrix-index>/<number>.json
+  # {
+  #   paths: [ [ ... ], ... ],
+  #   system: ...,
+  # }
+
+  #attrsSuperset = import ../../pkgs/test/release {
+  #  # Important: This is used to get dependencies for the evaluation itself.
+  #  # Because we don't want it to take forever on staging PRs,
+  #  # this uses the pinned CI version instead.
+  #  inherit pkgs;
+  #};
+
+  # How to get the list of supported systems?
+  # ci/supportedSystems.nix
+
+  #chunkResult =
+  #  {
+  #    # null means all default systems
+  #    # Pass a list of strings to select specific ones
+  #    system,
+  #    attrsSupersetFile,
+  #    myChunk,
+  #  }:
+  #  pkgs.runCommand "chunk-result-${system}-${toString myChunk}" ''
+  #  '';
+
+  #combinedResult =
+  #  {
+  #    chunkResults,
+  #  }:
+  #  pkgs.runCommand "combined-result" {
+  #    passAsFile = [ "jqScript" ];
+  #    jqScript = /* jq */ ''
+  #      split("\n") |
+  #      map(select(. != "") | split(" ") | map(select(. != ""))) |
+  #      map(
+  #          {
+  #              key: .[0],
+  #              value: .[1] | split(";") | map(split("=") |
+  #                 if length == 1 then
+  #                     { key: "out", value: .[0] }
+  #                 else
+  #                     { key: .[0], value: .[1] }
+  #                 end) | from_entries}
+  #      ) | from_entries
+  #    '';
+  #  } ''
+  #    cat ${lib.escapeShellArgs chunkResults} |
+  #      jq --raw-input --slurp -f "$jqScriptPath" "$tmpdir/paths" \
+  #      > $out/outpaths.json
+  #  '';
+in
+{
+  inherit attrpathsSuperset evalPlan singleSystem;
+}
diff --git a/ci/eval/parallel.nix b/ci/eval/parallel.nix
new file mode 100644
index 0000000000000..624df9dea377a
--- /dev/null
+++ b/ci/eval/parallel.nix
@@ -0,0 +1,42 @@
+/*
+*/
+{
+  lib ? import ../../lib,
+  path ? ../..,
+  chunkFile,
+}:
+
+let
+  chunk = lib.importJSON chunkFile;
+
+  unfiltered = import ../../pkgs/top-level/release-outpaths.nix {
+    inherit path;
+    inherit (chunk) checkMeta includeBroken systems;
+  };
+
+  filtered =
+    let
+      recurse =
+        index: paths: attrs:
+        lib.mapAttrs (
+          name: values:
+          if attrs ? ${name} then
+            if lib.any (value: lib.length value <= index + 1) values then
+              attrs.${name}
+            else
+              recurse (index + 1) values attrs.${name}
+          else
+            null
+        ) (lib.groupBy (a: lib.elemAt a index) paths);
+    in
+    recurse 0 chunk.paths unfiltered;
+
+  recurseEverywhere =
+    val:
+    if lib.isDerivation val || !(lib.isAttrs val) then
+      val
+    else
+      (lib.mapAttrs (_: v: recurseEverywhere v) val) // { recurseForDerivations = true; };
+
+in
+recurseEverywhere filtered
diff --git a/ci/parallel.nix b/ci/parallel.nix
deleted file mode 100644
index 074c545fe1170..0000000000000
--- a/ci/parallel.nix
+++ /dev/null
@@ -1,63 +0,0 @@
-/*
-  Invocation:
-
-  Invocation; note that the number of processes spawned is four times
-  the number of cores -- this helps in two ways:
-
-  1. Keeping cores busy while I/O operations are in flight
-
-  2. Since the amount of time needed for the jobs is *not* balanced
-     this minimizes the "tail latency" for the very last job to finish
-     (on one core) by making the job size smaller.
-*/
-# see pkgs/top-level/nohydra
-{
-  lib ? import ../lib,
-  checkMeta,
-  includeBroken ? true,
-  path ? ./..,
-  systems,
-  myChunk,
-  numChunks,
-  attrPathFile,
-}:
-
-let
-  attrPaths = builtins.fromJSON (builtins.readFile attrPathFile);
-  chunkSize = (lib.length attrPaths) / numChunks;
-  myPaths =
-    let
-      dropped = lib.drop (chunkSize * myChunk) attrPaths;
-    in
-    if myChunk == numChunks - 1 then dropped else lib.take chunkSize dropped;
-
-  unfiltered = import ../pkgs/top-level/release-outpaths.nix {
-    inherit
-      checkMeta
-      path
-      includeBroken
-      systems
-      ;
-  };
-
-  f =
-    i: m: a:
-    lib.mapAttrs (
-      name: values:
-      if a ? ${name} then
-        if lib.any (value: lib.length value <= i + 1) values then a.${name} else f (i + 1) values a.${name}
-      else
-        null
-    ) (lib.groupBy (a: lib.elemAt a i) m);
-
-  filtered = f 0 myPaths unfiltered;
-
-  recurseEverywhere =
-    val:
-    if lib.isDerivation val || !(lib.isAttrs val) then
-      val
-    else
-      (builtins.mapAttrs (_: v: recurseEverywhere v) val) // { recurseForDerivations = true; };
-
-in
-recurseEverywhere filtered
diff --git a/ci/supportedSystems.nix b/ci/supportedSystems.nix
new file mode 100644
index 0000000000000..0036f02f6b134
--- /dev/null
+++ b/ci/supportedSystems.nix
@@ -0,0 +1,7 @@
+[
+  "aarch64-linux"
+  "aarch64-darwin"
+  #"i686-linux"  # !!!
+  "x86_64-linux"
+  "x86_64-darwin"
+]
diff --git a/lib/tests/release.nix b/lib/tests/release.nix
index 084fbd94d34c2..5334498d08449 100644
--- a/lib/tests/release.nix
+++ b/lib/tests/release.nix
@@ -14,19 +14,5 @@ let
 in
   pkgs.symlinkJoin {
     name = "nixpkgs-lib-tests";
-    paths = map testWithNix nixVersions ++
-
-      #
-      # TEMPORARY MIGRATION MECHANISM
-      #
-      # This comment and the expression which follows it should be
-      # removed as part of resolving this issue:
-      #
-      #   https://github.com/NixOS/nixpkgs/issues/272591
-      #
-      [(import ../../pkgs/test/release {
-        inherit pkgs lib nix;
-      })]
-    ;
-
+    paths = map testWithNix nixVersions;
   }
diff --git a/pkgs/top-level/release-haskell.nix b/pkgs/top-level/release-haskell.nix
index 7a5a87ccf42e4..7df396f4327fc 100644
--- a/pkgs/top-level/release-haskell.nix
+++ b/pkgs/top-level/release-haskell.nix
@@ -9,7 +9,7 @@
 
   $ hydra-eval-jobs -I . pkgs/top-level/release-haskell.nix
 */
-{ supportedSystems ? [ "x86_64-linux" "x86_64-darwin" "aarch64-linux" "aarch64-darwin" ] }:
+{ supportedSystems ? import ../../ci/supportedSystems.nix }:
 
 let
 
diff --git a/pkgs/top-level/release-outpaths.nix b/pkgs/top-level/release-outpaths.nix
index 5c433fa542e0c..fd54609efa51b 100644
--- a/pkgs/top-level/release-outpaths.nix
+++ b/pkgs/top-level/release-outpaths.nix
@@ -12,13 +12,7 @@
 , attrNamesOnly ? false
 
 # Set this to `null` to build for builtins.currentSystem only
-, systems ? [
-    "aarch64-linux"
-    "aarch64-darwin"
-    #"i686-linux"  # !!!
-    "x86_64-linux"
-    "x86_64-darwin"
-  ]
+, systems ? import ../../ci/supportedSystems.nix
 }:
 let
   lib = import (path + "/lib");
diff --git a/pkgs/top-level/release.nix b/pkgs/top-level/release.nix
index 3d9de8660282b..25c28e8ff57aa 100644
--- a/pkgs/top-level/release.nix
+++ b/pkgs/top-level/release.nix
@@ -12,7 +12,7 @@
 , system ? builtins.currentSystem
 , officialRelease ? false
   # The platform doubles for which we build Nixpkgs.
-, supportedSystems ? [ "x86_64-linux" "x86_64-darwin" "aarch64-linux" "aarch64-darwin" ]
+, supportedSystems ? import ../../ci/supportedSystems.nix
   # The platform triples for which we build bootstrap tools.
 , bootstrapConfigs ? [
     "aarch64-apple-darwin"