diff --git a/Makefile b/Makefile
index 41f14ac92..3dae8b394 100644
--- a/Makefile
+++ b/Makefile
@@ -61,7 +61,7 @@ include mk/lib.mk
 # by the library. Rules are not "lazy" like variables, unfortunately.
 ifeq ($(ENABLE_BUILD), yes)
 $(eval $(call include-sub-makefile, doc/manual/local.mk))
-$(eval $(call include-sub-makefile, doc/internal-api/local.mk))
 endif
+$(eval $(call include-sub-makefile, doc/internal-api/local.mk))
 
 GLOBAL_CXXFLAGS += -g -Wall -include $(buildprefix)config.h -std=c++2a -I src
diff --git a/configure.ac b/configure.ac
index f8b937eb5..f9ad3c840 100644
--- a/configure.ac
+++ b/configure.ac
@@ -122,7 +122,6 @@ AC_PATH_PROG(flex, flex, false)
 AC_PATH_PROG(bison, bison, false)
 AC_PATH_PROG(dot, dot)
 AC_PATH_PROG(lsof, lsof, lsof)
-NEED_PROG(jq, jq)
 
 
 AC_SUBST(coreutils, [$(dirname $(type -p cat))])
@@ -133,6 +132,30 @@ AC_ARG_WITH(store-dir, AS_HELP_STRING([--with-store-dir=PATH],[path of the Nix s
 AC_SUBST(storedir)
 
 
+# Running the functional tests without building Nix is useful for testing
+# different pre-built versions of Nix against each other.
+AC_ARG_ENABLE(build, AS_HELP_STRING([--disable-build],[Do not build nix]),
+  ENABLE_BUILD=$enableval, ENABLE_BUILD=yes)
+AC_SUBST(ENABLE_BUILD)
+
+# Building without tests is useful for bootstrapping with a smaller footprint
+# or running the tests in a separate derivation. Otherwise, we do compile and
+# run them.
+AC_ARG_ENABLE(tests, AS_HELP_STRING([--disable-tests],[Do not build the tests]),
+  ENABLE_TESTS=$enableval, ENABLE_TESTS=yes)
+AC_SUBST(ENABLE_TESTS)
+
+# Building without API docs is the default as Nix' C++ interfaces are internal and unstable.
+AC_ARG_ENABLE(internal_api_docs, AS_HELP_STRING([--enable-internal-api-docs],[Build API docs for Nix's internal unstable C++ interfaces]),
+  internal_api_docs=$enableval, internal_api_docs=no)
+AC_SUBST(internal_api_docs)
+
+AS_IF(
+  [test "$ENABLE_BUILD" == "yes" || test "$ENABLE_TEST" == "yes"],
+  [NEED_PROG(jq, jq)])
+
+AS_IF([test "$ENABLE_BUILD" == "yes"],[
+
 # Look for boost, a required dependency.
 # Note that AX_BOOST_BASE only exports *CPP* BOOST_CPPFLAGS, no CXX flags,
 # and CPPFLAGS are not passed to the C++ compiler automatically.
@@ -155,18 +178,6 @@ if test "x$GCC_ATOMIC_BUILTINS_NEED_LIBATOMIC" = xyes; then
     LDFLAGS="-latomic $LDFLAGS"
 fi
 
-# Running the functional tests without building Nix is useful for testing
-# different pre-built versions of Nix against each other.
-AC_ARG_ENABLE(build, AS_HELP_STRING([--disable-build],[Do not build nix]),
-  ENABLE_BUILD=$enableval, ENABLE_BUILD=yes)
-AC_SUBST(ENABLE_BUILD)
-# Building without tests is useful for bootstrapping with a smaller footprint
-# or running the tests in a separate derivation. Otherwise, we do compile and
-# run them.
-AC_ARG_ENABLE(tests, AS_HELP_STRING([--disable-tests],[Do not build the tests]),
-  ENABLE_TESTS=$enableval, ENABLE_TESTS=yes)
-AC_SUBST(ENABLE_TESTS)
-
 AC_ARG_ENABLE(install-unit-tests, AS_HELP_STRING([--enable-install-unit-tests],[Install the unit tests for running later (default no)]),
   INSTALL_UNIT_TESTS=$enableval, INSTALL_UNIT_TESTS=no)
 AC_SUBST(INSTALL_UNIT_TESTS)
@@ -179,11 +190,6 @@ AC_ARG_WITH(check-lib-dir, AS_HELP_STRING([--with-check-lib-dir=PATH],[path to i
   checklibdir=$withval, checklibdir=$libdir)
 AC_SUBST(checklibdir)
 
-# Building without API docs is the default as Nix' C++ interfaces are internal and unstable.
-AC_ARG_ENABLE(internal_api_docs, AS_HELP_STRING([--enable-internal-api-docs],[Build API docs for Nix's internal unstable C++ interfaces]),
-  internal_api_docs=$enableval, internal_api_docs=no)
-AC_SUBST(internal_api_docs)
-
 # LTO is currently broken with clang for unknown reasons; ld segfaults in the llvm plugin
 AC_ARG_ENABLE(lto, AS_HELP_STRING([--enable-lto],[Enable LTO (only supported with GCC) [default=no]]),
   lto=$enableval, lto=no)
@@ -310,8 +316,7 @@ if test "$gc" = yes; then
   AC_DEFINE(HAVE_BOEHMGC, 1, [Whether to use the Boehm garbage collector.])
 fi
 
-
-if test "$ENABLE_TESTS" = yes; then
+AS_IF([test "$ENABLE_TESTS" == "yes"],[
 
 # Look for gtest.
 PKG_CHECK_MODULES([GTEST], [gtest_main])
@@ -338,12 +343,11 @@ AC_LINK_IFELSE([
   [AC_MSG_ERROR([librapidcheck is not found.])])
 AC_LANG_POP(C++)
 
-fi
+])
 
 # Look for nlohmann/json.
 PKG_CHECK_MODULES([NLOHMANN_JSON], [nlohmann_json >= 3.9])
 
-
 # documentation generation switch
 AC_ARG_ENABLE(doc-gen, AS_HELP_STRING([--disable-doc-gen],[disable documentation generation]),
   doc_generate=$enableval, doc_generate=yes)
@@ -388,6 +392,8 @@ if test "$embedded_sandbox_shell" = yes; then
   AC_DEFINE(HAVE_EMBEDDED_SANDBOX_SHELL, 1, [Include the sandbox shell in the Nix binary.])
 fi
 
+])
+
 
 # Expand all variables in config.status.
 test "$prefix" = NONE && prefix=$ac_default_prefix
diff --git a/flake.nix b/flake.nix
index ada52c05d..c7ff7eb64 100644
--- a/flake.nix
+++ b/flake.nix
@@ -17,11 +17,19 @@
   inputs.flake-compat = { url = "github:edolstra/flake-compat"; flake = false; };
   inputs.libgit2 = { url = "github:libgit2/libgit2"; flake = false; };
 
-  outputs = { self, nixpkgs, nixpkgs-regression, lowdown-src, flake-compat, libgit2 }:
+  outputs = { self, nixpkgs, nixpkgs-regression, lowdown-src, libgit2, ... }:
 
     let
       inherit (nixpkgs) lib;
 
+      # Experimental fileset library: https://github.com/NixOS/nixpkgs/pull/222981
+      # Not an "idiomatic" flake input because:
+      #  - Propagation to dependent locks: https://github.com/NixOS/nix/issues/7730
+      #  - Subflake would download redundant and huge parent flake
+      #  - No git tree hash support: https://github.com/NixOS/nix/issues/6044
+      inherit (import (builtins.fetchTarball { url = "https://github.com/NixOS/nix/archive/1bdcd7fc8a6a40b2e805bad759b36e64e911036b.tar.gz"; sha256 = "sha256:14ljlpdsp4x7h1fkhbmc4bd3vsqnx8zdql4h3037wh09ad6a0893"; }))
+        fileset;
+
       officialRelease = false;
 
       # Set to true to build the release notes for the next release.
@@ -53,7 +61,14 @@
         "x86_64-w64-mingw32"
       ];
 
-      stdenvs = [ "gccStdenv" "clangStdenv" "clang11Stdenv" "stdenv" "libcxxStdenv" "ccacheStdenv" ];
+      stdenvs = [
+        "ccacheStdenv"
+        "clang11Stdenv"
+        "clangStdenv"
+        "gccStdenv"
+        "libcxxStdenv"
+        "stdenv"
+      ];
 
       forAllSystems = lib.genAttrs systems;
 
@@ -68,57 +83,6 @@
             })
             stdenvs);
 
-      # Experimental fileset library: https://github.com/NixOS/nixpkgs/pull/222981
-      # Not an "idiomatic" flake input because:
-      #  - Propagation to dependent locks: https://github.com/NixOS/nix/issues/7730
-      #  - Subflake would download redundant and huge parent flake
-      #  - No git tree hash support: https://github.com/NixOS/nix/issues/6044
-      inherit (import (builtins.fetchTarball { url = "https://github.com/NixOS/nix/archive/1bdcd7fc8a6a40b2e805bad759b36e64e911036b.tar.gz"; sha256 = "sha256:14ljlpdsp4x7h1fkhbmc4bd3vsqnx8zdql4h3037wh09ad6a0893"; }))
-        fileset;
-
-      baseFiles =
-        # .gitignore has already been processed, so any changes in it are irrelevant
-        # at this point. It is not represented verbatim for test purposes because
-        # that would interfere with repo semantics.
-        fileset.fileFilter (f: f.name != ".gitignore") ./.;
-
-      configureFiles = fileset.unions [
-        ./.version
-        ./configure.ac
-        ./m4
-        # TODO: do we really need README.md? It doesn't seem used in the build.
-        ./README.md
-      ];
-
-      topLevelBuildFiles = fileset.unions [
-        ./local.mk
-        ./Makefile
-        ./Makefile.config.in
-        ./mk
-      ];
-
-      functionalTestFiles = fileset.unions [
-        ./tests/functional
-        (fileset.fileFilter (f: lib.strings.hasPrefix "nix-profile" f.name) ./scripts)
-      ];
-
-      nixSrc = fileset.toSource {
-        root = ./.;
-        fileset = fileset.intersect baseFiles (fileset.unions [
-          configureFiles
-          topLevelBuildFiles
-          ./boehmgc-coroutine-sp-fallback.diff
-          ./doc
-          ./misc
-          ./precompiled-headers.h
-          ./src
-          ./tests/unit
-          ./COPYING
-          ./scripts/local.mk
-          functionalTestFiles
-        ]);
-      };
-
       # Memoize nixpkgs for different platforms for efficiency.
       nixpkgsFor = forAllSystems
         (system: let
@@ -143,408 +107,121 @@
           cross = lib.genAttrs shellCrossSystems (crossSystem: make-pkgs crossSystem "stdenv");
         });
 
-      commonDeps =
-        { pkgs
-        , isStatic ? pkgs.stdenv.hostPlatform.isStatic
-        }:
-        with pkgs; rec {
-        # Use "busybox-sandbox-shell" if present,
-        # if not (legacy) fallback and hope it's sufficient.
-        sh = pkgs.busybox-sandbox-shell or (busybox.override {
-          useMusl = true;
-          enableStatic = true;
-          enableMinimal = true;
-          extraConfig = ''
-            CONFIG_FEATURE_FANCY_ECHO y
-            CONFIG_FEATURE_SH_MATH y
-            CONFIG_FEATURE_SH_MATH_64 y
-
-            CONFIG_ASH y
-            CONFIG_ASH_OPTIMIZE_FOR_SIZE y
-
-            CONFIG_ASH_ALIAS y
-            CONFIG_ASH_BASH_COMPAT y
-            CONFIG_ASH_CMDCMD y
-            CONFIG_ASH_ECHO y
-            CONFIG_ASH_GETOPTS y
-            CONFIG_ASH_INTERNAL_GLOB y
-            CONFIG_ASH_JOB_CONTROL y
-            CONFIG_ASH_PRINTF y
-            CONFIG_ASH_TEST y
-          '';
-        });
-
-        configureFlags =
-          lib.optionals stdenv.isLinux [
-            "--with-boost=${boost}/lib"
-            "--with-sandbox-shell=${sh}/bin/busybox"
-          ]
-          ++ lib.optionals (stdenv.isLinux && !(isStatic && stdenv.system == "aarch64-linux")) [
-            "LDFLAGS=-fuse-ld=gold"
-          ];
-
-        testConfigureFlags = [
-          "RAPIDCHECK_HEADERS=${lib.getDev rapidcheck}/extras/gtest/include"
-        ] ++ lib.optionals (stdenv.hostPlatform != stdenv.buildPlatform) [
-          "--enable-install-unit-tests"
-          "--with-check-bin-dir=${builtins.placeholder "check"}/bin"
-          "--with-check-lib-dir=${builtins.placeholder "check"}/lib"
-        ];
-
-        internalApiDocsConfigureFlags = [
-          "--enable-internal-api-docs"
-        ];
-
-        changelog-d = pkgs.buildPackages.callPackage ./misc/changelog-d.nix { };
-
-        nativeBuildDeps =
-          [
-            buildPackages.bison
-            buildPackages.flex
-            (lib.getBin buildPackages.lowdown-nix)
-            buildPackages.mdbook
-            buildPackages.mdbook-linkcheck
-            buildPackages.autoconf-archive
-            buildPackages.autoreconfHook
-            buildPackages.pkg-config
-
-            # Tests
-            buildPackages.git
-            buildPackages.mercurial # FIXME: remove? only needed for tests
-            buildPackages.jq # Also for custom mdBook preprocessor.
-            buildPackages.openssh # only needed for tests (ssh-keygen)
-          ]
-          ++ lib.optionals stdenv.hostPlatform.isLinux [(buildPackages.util-linuxMinimal or buildPackages.utillinuxMinimal)]
-          # Official releases don't have rl-next, so we don't need to compile a changelog
-          ++ lib.optional (!officialRelease && buildUnreleasedNotes) changelog-d
-          ;
-
-        buildDeps =
-          [ curl
-            bzip2 xz brotli
-            openssl sqlite
-            libarchive
-            (pkgs.libgit2.overrideAttrs (attrs: {
-              src = libgit2;
-              version = libgit2.lastModifiedDate;
-              cmakeFlags = (attrs.cmakeFlags or []) ++ ["-DUSE_SSH=exec"];
-            }))
-            boost
-            libsodium
-          ]
-          ++ lib.optionals (!stdenv.hostPlatform.isWindows) [
-            editline
-            lowdown-nix
-          ]
-          ++ lib.optional stdenv.isLinux libseccomp
-          ++ lib.optional stdenv.hostPlatform.isx86_64 libcpuid;
-
-        checkDeps = [
-          gtest
-          rapidcheck
-        ];
-
-        internalApiDocsDeps = [
-          buildPackages.doxygen
-        ];
-
-        awsDeps = lib.optional (stdenv.isLinux || stdenv.isDarwin)
-          (aws-sdk-cpp.override {
-            apis = ["s3" "transfer"];
-            customMemoryManagement = false;
-          });
-
-        propagatedDeps =
-          [ ((boehmgc.override {
-              enableLargeConfig = true;
-            }).overrideAttrs(o: {
-              patches = (o.patches or []) ++ [
-                ./boehmgc-coroutine-sp-fallback.diff
-
-                # https://github.com/ivmai/bdwgc/pull/586
-                ./boehmgc-traceable_allocator-public.diff
-              ];
-            })
-            )
-            nlohmann_json
-          ];
-      };
-
       installScriptFor = tarballs:
-        with nixpkgsFor.x86_64-linux.native;
-        runCommand "installer-script"
-          { buildInputs = [ nix ];
-          }
-          ''
-            mkdir -p $out/nix-support
-
-            # Converts /nix/store/50p3qk8k...-nix-2.4pre20201102_550e11f/bin/nix to 50p3qk8k.../bin/nix.
-            tarballPath() {
-              # Remove the store prefix
-              local path=''${1#${builtins.storeDir}/}
-              # Get the path relative to the derivation root
-              local rest=''${path#*/}
-              # Get the derivation hash
-              local drvHash=''${path%%-*}
-              echo "$drvHash/$rest"
-            }
-
-            substitute ${./scripts/install.in} $out/install \
-              ${pkgs.lib.concatMapStrings
-                (tarball: let
-                    inherit (tarball.stdenv.hostPlatform) system;
-                  in '' \
-                  --replace '@tarballHash_${system}@' $(nix --experimental-features nix-command hash-file --base16 --type sha256 ${tarball}/*.tar.xz) \
-                  --replace '@tarballPath_${system}@' $(tarballPath ${tarball}/*.tar.xz) \
-                  ''
-                )
-                tarballs
-              } --replace '@nixVersion@' ${version}
-
-            echo "file installer $out/install" >> $out/nix-support/hydra-build-products
-          '';
-
-      testNixVersions = pkgs: client: daemon: with commonDeps { inherit pkgs; }; with pkgs.lib; pkgs.stdenv.mkDerivation {
-        NIX_DAEMON_PACKAGE = daemon;
-        NIX_CLIENT_PACKAGE = client;
-        name =
-          "nix-tests"
-          + optionalString
-            (versionAtLeast daemon.version "2.4pre20211005" &&
-             versionAtLeast client.version "2.4pre20211005")
-            "-${client.version}-against-${daemon.version}";
-        inherit version;
-
-        src = fileset.toSource {
-          root = ./.;
-          fileset = fileset.intersect baseFiles (fileset.unions [
-            configureFiles
-            topLevelBuildFiles
-            functionalTestFiles
-          ]);
+        nixpkgsFor.x86_64-linux.native.callPackage ./scripts/installer.nix {
+          inherit tarballs;
         };
 
-        VERSION_SUFFIX = versionSuffix;
+      testNixVersions = pkgs: client: daemon:
+        pkgs.callPackage ./package.nix {
+          pname =
+            "nix-tests"
+            + lib.optionalString
+              (lib.versionAtLeast daemon.version "2.4pre20211005" &&
+               lib.versionAtLeast client.version "2.4pre20211005")
+              "-${client.version}-against-${daemon.version}";
 
-        nativeBuildInputs = nativeBuildDeps;
-        buildInputs = buildDeps ++ awsDeps ++ checkDeps;
-        propagatedBuildInputs = propagatedDeps;
+          inherit fileset;
 
-        enableParallelBuilding = true;
+          test-client = client;
+          test-daemon = daemon;
 
-        configureFlags =
-          testConfigureFlags # otherwise configure fails
-          ++ [ "--disable-build" ];
-        dontBuild = true;
-        doInstallCheck = true;
+          doBuild = false;
+        };
 
-        installPhase = ''
-          mkdir -p $out
-        '';
-
-        installCheckPhase = ''
-          mkdir -p src/nix-channel
-          make installcheck -j$NIX_BUILD_CORES -l$NIX_BUILD_CORES
-        '';
+      binaryTarball = nix: pkgs: pkgs.callPackage ./scripts/binary-tarball.nix {
+        inherit nix;
       };
 
-      binaryTarball = nix: pkgs:
-        let
-          inherit (pkgs) buildPackages;
-          inherit (pkgs) cacert;
-          installerClosureInfo = buildPackages.closureInfo { rootPaths = [ nix cacert ]; };
-        in
-
-        pkgs.runCommand "nix-binary-tarball-${version}"
-          { #nativeBuildInputs = lib.optional (system != "aarch64-linux") shellcheck;
-            meta.description = "Distribution-independent Nix bootstrap binaries for ${pkgs.system}";
-          }
-          ''
-            cp ${installerClosureInfo}/registration $TMPDIR/reginfo
-            cp ${./scripts/create-darwin-volume.sh} $TMPDIR/create-darwin-volume.sh
-            substitute ${./scripts/install-nix-from-closure.sh} $TMPDIR/install \
-              --subst-var-by nix ${nix} \
-              --subst-var-by cacert ${cacert}
-
-            substitute ${./scripts/install-darwin-multi-user.sh} $TMPDIR/install-darwin-multi-user.sh \
-              --subst-var-by nix ${nix} \
-              --subst-var-by cacert ${cacert}
-            substitute ${./scripts/install-systemd-multi-user.sh} $TMPDIR/install-systemd-multi-user.sh \
-              --subst-var-by nix ${nix} \
-              --subst-var-by cacert ${cacert}
-            substitute ${./scripts/install-multi-user.sh} $TMPDIR/install-multi-user \
-              --subst-var-by nix ${nix} \
-              --subst-var-by cacert ${cacert}
-
-            if type -p shellcheck; then
-              # SC1090: Don't worry about not being able to find
-              #         $nix/etc/profile.d/nix.sh
-              shellcheck --exclude SC1090 $TMPDIR/install
-              shellcheck $TMPDIR/create-darwin-volume.sh
-              shellcheck $TMPDIR/install-darwin-multi-user.sh
-              shellcheck $TMPDIR/install-systemd-multi-user.sh
-
-              # SC1091: Don't panic about not being able to source
-              #         /etc/profile
-              # SC2002: Ignore "useless cat" "error", when loading
-              #         .reginfo, as the cat is a much cleaner
-              #         implementation, even though it is "useless"
-              # SC2116: Allow ROOT_HOME=$(echo ~root) for resolving
-              #         root's home directory
-              shellcheck --external-sources \
-                --exclude SC1091,SC2002,SC2116 $TMPDIR/install-multi-user
-            fi
-
-            chmod +x $TMPDIR/install
-            chmod +x $TMPDIR/create-darwin-volume.sh
-            chmod +x $TMPDIR/install-darwin-multi-user.sh
-            chmod +x $TMPDIR/install-systemd-multi-user.sh
-            chmod +x $TMPDIR/install-multi-user
-            dir=nix-${version}-${pkgs.system}
-            fn=$out/$dir.tar.xz
-            mkdir -p $out/nix-support
-            echo "file binary-dist $fn" >> $out/nix-support/hydra-build-products
-            tar cvfJ $fn \
-              --owner=0 --group=0 --mode=u+rw,uga+r \
-              --mtime='1970-01-01' \
-              --absolute-names \
-              --hard-dereference \
-              --transform "s,$TMPDIR/install,$dir/install," \
-              --transform "s,$TMPDIR/create-darwin-volume.sh,$dir/create-darwin-volume.sh," \
-              --transform "s,$TMPDIR/reginfo,$dir/.reginfo," \
-              --transform "s,$NIX_STORE,$dir/store,S" \
-              $TMPDIR/install \
-              $TMPDIR/create-darwin-volume.sh \
-              $TMPDIR/install-darwin-multi-user.sh \
-              $TMPDIR/install-systemd-multi-user.sh \
-              $TMPDIR/install-multi-user \
-              $TMPDIR/reginfo \
-              $(cat ${installerClosureInfo}/store-paths)
-          '';
-
       overlayFor = getStdenv: final: prev:
-        let currentStdenv = getStdenv final; in
+        let
+          stdenv = getStdenv final;
+        in
         {
           nixStable = prev.nix;
 
           # Forward from the previous stage as we don’t want it to pick the lowdown override
-          nixUnstable = prev.nixUnstable;
+          inherit (prev) nixUnstable;
 
-          nix =
-          with final;
-          with commonDeps {
-            inherit pkgs;
-            inherit (currentStdenv.hostPlatform) isStatic;
-          };
-          let
-            canRunInstalled = currentStdenv.buildPlatform.canExecute currentStdenv.hostPlatform;
-          in currentStdenv.mkDerivation (finalAttrs: {
-            name = "nix-${version}";
-            inherit version;
+          default-busybox-sandbox-shell = final.busybox.override {
+            useMusl = true;
+            enableStatic = true;
+            enableMinimal = true;
+            extraConfig = ''
+              CONFIG_FEATURE_FANCY_ECHO y
+              CONFIG_FEATURE_SH_MATH y
+              CONFIG_FEATURE_SH_MATH_64 y
 
-            src = nixSrc;
-            VERSION_SUFFIX = versionSuffix;
+              CONFIG_ASH y
+              CONFIG_ASH_OPTIMIZE_FOR_SIZE y
 
-            outputs = [ "out" "dev" "doc" ]
-              ++ lib.optional (currentStdenv.hostPlatform != currentStdenv.buildPlatform) "check";
-
-            nativeBuildInputs = nativeBuildDeps;
-            buildInputs = buildDeps
-              # There have been issues building these dependencies
-              ++ lib.optionals (currentStdenv.hostPlatform == currentStdenv.buildPlatform) awsDeps
-              ++ lib.optionals finalAttrs.doCheck checkDeps;
-
-            propagatedBuildInputs = propagatedDeps;
-
-            disallowedReferences = [ boost ];
-
-            preConfigure = lib.optionalString (! currentStdenv.hostPlatform.isStatic)
-              ''
-                # Copy libboost_context so we don't get all of Boost in our closure.
-                # https://github.com/NixOS/nixpkgs/issues/45462
-                mkdir -p $out/lib
-                cp -pd ${boost}/lib/{libboost_context*,libboost_thread*,libboost_system*} $out/lib
-                rm -f $out/lib/*.a
-                ${lib.optionalString currentStdenv.hostPlatform.isLinux ''
-                  chmod u+w $out/lib/*.so.*
-                  patchelf --set-rpath $out/lib:${currentStdenv.cc.cc.lib}/lib $out/lib/libboost_thread.so.*
-                ''}
-                ${lib.optionalString currentStdenv.hostPlatform.isDarwin ''
-                  for LIB in $out/lib/*.dylib; do
-                    chmod u+w $LIB
-                    install_name_tool -id $LIB $LIB
-                    install_name_tool -delete_rpath ${boost}/lib/ $LIB || true
-                  done
-                  install_name_tool -change ${boost}/lib/libboost_system.dylib $out/lib/libboost_system.dylib $out/lib/libboost_thread.dylib
-                ''}
-              '';
-
-            configureFlags = configureFlags ++
-              [ "--sysconfdir=/etc" ] ++
-              lib.optional stdenv.hostPlatform.isStatic "--enable-embedded-sandbox-shell" ++
-              [ (lib.enableFeature finalAttrs.doCheck "tests") ] ++
-              lib.optionals finalAttrs.doCheck testConfigureFlags ++
-              lib.optional (!canRunInstalled) "--disable-doc-gen";
-
-            enableParallelBuilding = true;
-
-            makeFlags = "profiledir=$(out)/etc/profile.d PRECOMPILE_HEADERS=1";
-
-            doCheck = true;
-
-            installFlags = "sysconfdir=$(out)/etc";
-
-            postInstall = ''
-              mkdir -p $doc/nix-support
-              echo "doc manual $doc/share/doc/nix/manual" >> $doc/nix-support/hydra-build-products
-              ${lib.optionalString currentStdenv.hostPlatform.isStatic ''
-              mkdir -p $out/nix-support
-              echo "file binary-dist $out/bin/nix" >> $out/nix-support/hydra-build-products
-              ''}
-              ${lib.optionalString currentStdenv.isDarwin ''
-              install_name_tool \
-                -change ${boost}/lib/libboost_context.dylib \
-                $out/lib/libboost_context.dylib \
-                $out/lib/libnixutil.dylib
-              ''}
+              CONFIG_ASH_ALIAS y
+              CONFIG_ASH_BASH_COMPAT y
+              CONFIG_ASH_CMDCMD y
+              CONFIG_ASH_ECHO y
+              CONFIG_ASH_GETOPTS y
+              CONFIG_ASH_INTERNAL_GLOB y
+              CONFIG_ASH_JOB_CONTROL y
+              CONFIG_ASH_PRINTF y
+              CONFIG_ASH_TEST y
             '';
+          };
 
-            doInstallCheck = finalAttrs.doCheck;
-            installCheckFlags = "sysconfdir=$(out)/etc";
-            installCheckTarget = "installcheck"; # work around buggy detection in stdenv
+          lowdown-nix = final.callPackage ./misc/lowdown.nix {
+            inherit lowdown-src stdenv;
+          };
 
-            separateDebugInfo = !currentStdenv.hostPlatform.isStatic;
-
-            strictDeps = true;
-
-            hardeningDisable = lib.optional stdenv.hostPlatform.isStatic "pie";
-
-            passthru.perl-bindings = final.callPackage ./perl {
-              inherit fileset;
-              stdenv = currentStdenv;
-            };
-
-            meta.platforms = lib.platforms.unix ++ lib.platforms.windows;
-            meta.mainProgram = "nix";
+          libgit2-nix = final.libgit2.overrideAttrs (attrs: {
+            src = libgit2;
+            version = libgit2.lastModifiedDate;
+            cmakeFlags = attrs.cmakeFlags or []
+              ++ [ "-DUSE_SSH=exec" ];
           });
 
-          lowdown-nix = with final; currentStdenv.mkDerivation rec {
-            name = "lowdown-0.9.0";
+          boehmgc-nix = (final.boehmgc.override {
+            enableLargeConfig = true;
+          }).overrideAttrs(o: {
+            patches = (o.patches or []) ++ [
+              ./boehmgc-coroutine-sp-fallback.diff
 
-            src = lowdown-src;
+              # https://github.com/ivmai/bdwgc/pull/586
+              ./boehmgc-traceable_allocator-public.diff
+            ];
+          });
 
-            outputs = [ "out" "bin" "dev" ];
+          changelog-d-nix = final.buildPackages.callPackage ./misc/changelog-d.nix { };
 
-            nativeBuildInputs = [ buildPackages.which ];
+          nix =
+            let
+              officialRelease = false;
+              versionSuffix =
+                if officialRelease
+                then ""
+                else "pre${builtins.substring 0 8 (self.lastModifiedDate or self.lastModified or "19700101")}_${self.shortRev or "dirty"}";
+
+            in final.callPackage ./package.nix {
+              inherit
+                fileset
+                stdenv
+                versionSuffix
+                ;
+              officialRelease = false;
+              boehmgc = final.boehmgc-nix;
+              libgit2 = final.libgit2-nix;
+              lowdown = final.lowdown-nix;
+              busybox-sandbox-shell = final.busybox-sandbox-shell or final.default-busybox-sandbox-shell;
+              changelog-d = final.changelog-d-nix;
+            } // {
+              # this is a proper separate downstream package, but put
+              # here also for back compat reasons.
+              perl-bindings = final.nix-perl-bindings;
+            };
+
+            nix-perl-bindings = final.callPackage ./perl {
+              inherit fileset stdenv;
+            };
 
-            configurePhase = ''
-                ${if (currentStdenv.isDarwin && currentStdenv.isAarch64) then "echo \"HAVE_SANDBOX_INIT=false\" > configure.local" else ""}
-                ./configure \
-                  PREFIX=${placeholder "dev"} \
-                  BINDIR=${placeholder "bin"}/bin
-            '';
           };
-        };
 
     in {
       # A Nixpkgs overlay that overrides the 'nix' and
@@ -615,60 +292,17 @@
         dockerImage = lib.genAttrs linux64BitSystems (system: self.packages.${system}.dockerImage);
 
         # Line coverage analysis.
-        coverage =
-          with nixpkgsFor.x86_64-linux.native;
-          with commonDeps { inherit pkgs; };
-
-          releaseTools.coverageAnalysis {
-            name = "nix-coverage-${version}";
-
-            src = nixSrc;
-
-            configureFlags = testConfigureFlags;
-
-            enableParallelBuilding = true;
-
-            nativeBuildInputs = nativeBuildDeps;
-            buildInputs = buildDeps ++ propagatedDeps ++ awsDeps ++ checkDeps;
-
-            dontInstall = false;
-
-            doInstallCheck = true;
-            installCheckTarget = "installcheck"; # work around buggy detection in stdenv
-
-            lcovFilter = [ "*/boost/*" "*-tab.*" ];
-
-            hardeningDisable = ["fortify"];
-
-            NIX_CFLAGS_COMPILE = "-DCOVERAGE=1";
-          };
+        coverage = nixpkgsFor.x86_64-linux.native.nix.override {
+          pname = "nix-coverage";
+          withCoverageChecks = true;
+        };
 
         # API docs for Nix's unstable internal C++ interfaces.
-        internal-api-docs =
-          with nixpkgsFor.x86_64-linux.native;
-          with commonDeps { inherit pkgs; };
-
-          stdenv.mkDerivation {
-            pname = "nix-internal-api-docs";
-            inherit version;
-
-            src = nixSrc;
-
-            configureFlags = testConfigureFlags ++ internalApiDocsConfigureFlags;
-
-            nativeBuildInputs = nativeBuildDeps;
-            buildInputs = buildDeps ++ propagatedDeps
-              ++ awsDeps ++ checkDeps ++ internalApiDocsDeps;
-
-            dontBuild = true;
-
-            installTargets = [ "internal-api-html" ];
-
-            postInstall = ''
-              mkdir -p $out/nix-support
-              echo "doc internal-api-docs $out/share/doc/nix/internal-api/html" >> $out/nix-support/hydra-build-products
-            '';
-          };
+        internal-api-docs = nixpkgsFor.x86_64-linux.native.callPackage ./package.nix {
+          inherit fileset;
+          doBuild = false;
+          enableInternalAPIDocs = true;
+        };
 
         # System tests.
         tests = import ./tests/nixos { inherit lib nixpkgs nixpkgsFor; } // {
@@ -676,7 +310,9 @@
           # Make sure that nix-env still produces the exact same result
           # on a particular version of Nixpkgs.
           evalNixpkgs =
-            with nixpkgsFor.x86_64-linux.native;
+            let
+              inherit (nixpkgsFor.x86_64-linux.native) runCommand nix;
+            in
             runCommand "eval-nixos" { buildInputs = [ nix ]; }
               ''
                 type -p nix-env
@@ -729,7 +365,7 @@
         rl-next =
           let pkgs = nixpkgsFor.${system}.native;
           in pkgs.buildPackages.runCommand "test-rl-next-release-notes" { } ''
-          LANG=C.UTF-8 ${(commonDeps { inherit pkgs; }).changelog-d}/bin/changelog-d ${./doc/manual/rl-next} >$out
+          LANG=C.UTF-8 ${pkgs.changelog-d-nix}/bin/changelog-d ${./doc/manual/rl-next} >$out
         '';
       } // (lib.optionalAttrs (builtins.elem system linux64BitSystems)) {
         dockerImage = self.hydraJobs.dockerImage.${system};
@@ -768,47 +404,17 @@
           stdenvs)));
 
       devShells = let
-        makeShell = pkgs: stdenv:
-          let
-            canRunInstalled = stdenv.buildPlatform.canExecute stdenv.hostPlatform;
-          in
-          with commonDeps { inherit pkgs; };
-          stdenv.mkDerivation {
-            name = "nix";
+        makeShell = pkgs: stdenv: (pkgs.nix.override { inherit stdenv; }).overrideAttrs (_: {
+          installFlags = "sysconfdir=$(out)/etc";
+          shellHook = ''
+            PATH=$prefix/bin:$PATH
+            unset PYTHONPATH
+            export MANPATH=$out/share/man:$MANPATH
 
-            outputs = [ "out" "dev" "doc" ]
-              ++ lib.optional (stdenv.hostPlatform != stdenv.buildPlatform) "check";
-
-            nativeBuildInputs = nativeBuildDeps
-              ++ lib.optional stdenv.cc.isClang pkgs.buildPackages.bear
-              ++ lib.optional
-                (stdenv.cc.isClang && stdenv.hostPlatform == stdenv.buildPlatform)
-                pkgs.buildPackages.clang-tools
-              # We want changelog-d in the shell even if the current build doesn't need it
-              ++ lib.optional (officialRelease || ! buildUnreleasedNotes) changelog-d
-              ;
-
-            buildInputs = buildDeps ++ propagatedDeps
-              ++ awsDeps ++ checkDeps ++ internalApiDocsDeps;
-
-            configureFlags = configureFlags
-              ++ testConfigureFlags ++ internalApiDocsConfigureFlags
-              ++ lib.optional (!canRunInstalled) "--disable-doc-gen";
-
-            enableParallelBuilding = true;
-
-            installFlags = "sysconfdir=$(out)/etc";
-
-            shellHook =
-              ''
-                PATH=$prefix/bin:$PATH
-                unset PYTHONPATH
-                export MANPATH=$out/share/man:$MANPATH
-
-                # Make bash completion work.
-                XDG_DATA_DIRS+=:$out/share
-              '';
-          };
+            # Make bash completion work.
+            XDG_DATA_DIRS+=:$out/share
+          '';
+        });
         in
         forAllSystems (system:
           let
diff --git a/misc/lowdown.nix b/misc/lowdown.nix
new file mode 100644
index 000000000..5f469fad5
--- /dev/null
+++ b/misc/lowdown.nix
@@ -0,0 +1,22 @@
+{ lib
+, stdenv
+, which
+, lowdown-src
+}:
+
+stdenv.mkDerivation rec {
+  name = "lowdown-0.9.0";
+
+  src = lowdown-src;
+
+  outputs = [ "out" "bin" "dev" ];
+
+  nativeBuildInputs = [ which ];
+
+  configurePhase = ''
+      ${lib.optionalString (stdenv.isDarwin && stdenv.isAarch64) "echo \"HAVE_SANDBOX_INIT=false\" > configure.local"}
+      ./configure \
+        PREFIX=${placeholder "dev"} \
+        BINDIR=${placeholder "bin"}/bin
+  '';
+}
diff --git a/package.nix b/package.nix
new file mode 100644
index 000000000..0b2ff43b0
--- /dev/null
+++ b/package.nix
@@ -0,0 +1,384 @@
+{ lib
+, stdenv
+, releaseTools
+, autoconf-archive
+, autoreconfHook
+, aws-sdk-cpp
+, boehmgc
+, nlohmann_json
+, bison
+, boost
+, brotli
+, bzip2
+, changelog-d
+, curl
+, editline
+, fileset
+, flex
+, git
+, gtest
+, jq
+, doxygen
+, libarchive
+, libcpuid
+, libgit2
+, libseccomp
+, libsodium
+, lowdown
+, mdbook
+, mdbook-linkcheck
+, mercurial
+, openssh
+, openssl
+, pkg-config
+, rapidcheck
+, sqlite
+, util-linux
+, xz
+
+, busybox-sandbox-shell ? null
+
+# Configuration Options
+#:
+# This probably seems like too many degrees of freedom, but it
+# faithfully reflects how the underlying configure + make build system
+# work. The top-level flake.nix will choose useful combinations of these
+# options to CI.
+
+, pname ? "nix"
+
+, versionSuffix ? ""
+, officialRelease ? false
+
+# Whether to build Nix. Useful to skip for tasks like (a) just
+# generating API docs or (b) testing existing pre-built versions of Nix
+, doBuild ? true
+
+# Run the unit tests as part of the build. See `installUnitTests` for an
+# alternative to this.
+, doCheck ? __forDefaults.canRunInstalled
+
+# Run the functional tests as part of the build.
+, doInstallCheck ? test-client != null || __forDefaults.canRunInstalled
+
+# Check test coverage of Nix. Probably want to use with with at least
+# one of `doCHeck` or `doInstallCheck` enabled.
+, withCoverageChecks ? false
+
+# Whether to build the regular manual
+, enableManual ? __forDefaults.canRunInstalled
+
+# Whether to compile `rl-next.md`, the release notes for the next
+# not-yet-released version of Nix in the manul, from the individual
+# change log entries in the directory.
+, buildUnreleasedNotes ? false
+
+# Whether to build the internal API docs, can be done separately from
+# everything else.
+, enableInternalAPIDocs ? false
+
+# Whether to install unit tests. This is useful when cross compiling
+# since we cannot run them natively during the build, but can do so
+# later.
+, installUnitTests ? __forDefaults.canRunInstalled
+
+# For running the functional tests against a pre-built Nix. Probably
+# want to use in conjunction with `doBuild = false;`.
+, test-daemon ? null
+, test-client ? null
+
+# Not a real argument, just the only way to approximate let-binding some
+# stuff for argument defaults.
+, __forDefaults ? {
+    canRunInstalled = doBuild && stdenv.buildPlatform.canExecute stdenv.hostPlatform;
+  }
+}:
+
+let
+  version = lib.fileContents ./.version + versionSuffix;
+
+  # selected attributes with defaults, will be used to define some
+  # things which should instead be gotten via `finalAttrs` in order to
+  # work with overriding.
+  attrs = {
+    inherit doBuild doCheck doInstallCheck;
+  };
+
+  filesets = {
+    baseFiles = fileset.fileFilter (f: f.name != ".gitignore") ./.;
+
+    configureFiles = fileset.unions [
+      ./.version
+      ./configure.ac
+      ./m4
+      # TODO: do we really need README.md? It doesn't seem used in the build.
+      ./README.md
+    ];
+
+    topLevelBuildFiles = fileset.unions [
+      ./local.mk
+      ./Makefile
+      ./Makefile.config.in
+      ./mk
+    ];
+
+    functionalTestFiles = fileset.unions [
+      ./tests/functional
+      (fileset.fileFilter (f: lib.strings.hasPrefix "nix-profile" f.name) ./scripts)
+    ];
+  };
+
+  mkDerivation =
+    if withCoverageChecks
+    then
+      # TODO support `finalAttrs` args function in
+      # `releaseTools.coverageAnalysis`.
+      argsFun:
+         releaseTools.coverageAnalysis (let args = argsFun args; in args)
+    else stdenv.mkDerivation;
+in
+
+mkDerivation (finalAttrs: let
+
+  inherit (finalAttrs)
+    doCheck
+    doInstallCheck
+    ;
+
+  doBuild = !finalAttrs.dontBuild;
+
+  # Either running the unit tests during the build, or installing them
+  # to be run later, requiresthe unit tests to be built.
+  buildUnitTests = doCheck || installUnitTests;
+
+  anySortOfTesting = buildUnitTests || doInstallCheck;
+
+in {
+  inherit pname version;
+
+  src =
+    let
+
+    in
+      fileset.toSource {
+        root = ./.;
+        fileset = fileset.intersect filesets.baseFiles (fileset.unions ([
+          filesets.configureFiles
+          filesets.topLevelBuildFiles
+          ./doc/internal-api
+        ] ++ lib.optionals doBuild [
+          ./boehmgc-coroutine-sp-fallback.diff
+          ./doc
+          ./misc
+          ./precompiled-headers.h
+          ./src
+          ./tests/unit
+          ./COPYING
+          ./scripts/local.mk
+        ] ++ lib.optionals anySortOfTesting [
+          filesets.functionalTestFiles
+        ]));
+      };
+
+  VERSION_SUFFIX = versionSuffix;
+
+  outputs = [ "out" ]
+    ++ lib.optional doBuild "dev"
+    # If we are doing just build or just docs, the one thing will use
+    # "out". We only need additional outputs if we are doing both.
+    ++ lib.optional (doBuild && (enableManual || enableInternalAPIDocs)) "doc"
+    ++ lib.optional installUnitTests "check";
+
+  nativeBuildInputs = [
+    autoconf-archive
+    autoreconfHook
+    pkg-config
+  ] ++ lib.optionals doBuild [
+    bison
+    flex
+  ] ++ lib.optionals enableManual [
+    (lib.getBin lowdown)
+    mdbook
+    mdbook-linkcheck
+  ] ++ lib.optionals (doInstallCheck || enableManual) [
+    jq # Also for custom mdBook preprocessor.
+  ] ++ lib.optional stdenv.hostPlatform.isLinux util-linux
+    # Official releases don't have rl-next, so we don't need to compile a
+    # changelog
+    ++ lib.optional (!officialRelease && buildUnreleasedNotes) changelog-d
+    ++ lib.optional enableInternalAPIDocs doxygen
+  ;
+
+  buildInputs = lib.optionals doBuild [
+    boost
+    brotli
+    bzip2
+    curl
+    libarchive
+    libgit2
+    libsodium
+    openssl
+    sqlite
+    xz
+  ] ++ lib.optionals (!stdenv.hostPlatform.isWindows) [
+    editline
+    lowdown
+  ] ++ lib.optional stdenv.isLinux libseccomp
+    ++ lib.optional stdenv.hostPlatform.isx86_64 libcpuid
+    # There have been issues building these dependencies
+    ++ lib.optional (stdenv.hostPlatform == stdenv.buildPlatform && (stdenv.isLinux || stdenv.isDarwin))
+      (aws-sdk-cpp.override {
+        apis = ["s3" "transfer"];
+        customMemoryManagement = false;
+      })
+  ;
+
+  propagatedBuildInputs = [
+    boehmgc
+    nlohmann_json
+  ];
+
+  dontBuild = !attrs.doBuild;
+  doCheck = attrs.doCheck;
+
+  checkInputs = [
+    gtest
+    rapidcheck
+  ];
+
+  nativeCheckInputs = [
+    git
+    mercurial
+    openssh
+  ];
+
+  disallowedReferences = [ boost ];
+
+  preConfigure = lib.optionalString (doBuild && ! stdenv.hostPlatform.isStatic) (
+    ''
+      # Copy libboost_context so we don't get all of Boost in our closure.
+      # https://github.com/NixOS/nixpkgs/issues/45462
+      mkdir -p $out/lib
+      cp -pd ${boost}/lib/{libboost_context*,libboost_thread*,libboost_system*,libboost_regex*} $out/lib
+      rm -f $out/lib/*.a
+    '' + lib.optionalString stdenv.hostPlatform.isLinux ''
+      chmod u+w $out/lib/*.so.*
+      patchelf --set-rpath $out/lib:${stdenv.cc.cc.lib}/lib $out/lib/libboost_thread.so.*
+    '' + lib.optionalString stdenv.hostPlatform.isDarwin ''
+      for LIB in $out/lib/*.dylib; do
+        chmod u+w $LIB
+        install_name_tool -id $LIB $LIB
+        install_name_tool -delete_rpath ${boost}/lib/ $LIB || true
+      done
+      install_name_tool -change ${boost}/lib/libboost_system.dylib $out/lib/libboost_system.dylib $out/lib/libboost_thread.dylib
+    ''
+  );
+
+  configureFlags = [
+    "--sysconfdir=/etc"
+    (lib.enableFeature doBuild "build")
+    (lib.enableFeature anySortOfTesting "tests")
+    (lib.enableFeature enableInternalAPIDocs "internal-api-docs")
+    (lib.enableFeature enableManual "doc-gen")
+    (lib.enableFeature installUnitTests "install-unit-tests")
+  ] ++ lib.optionals installUnitTests [
+    "--with-check-bin-dir=${builtins.placeholder "check"}/bin"
+    "--with-check-lib-dir=${builtins.placeholder "check"}/lib"
+  ] ++ lib.optionals (doBuild && stdenv.isLinux) [
+    "--with-boost=${boost}/lib"
+    "--with-sandbox-shell=${busybox-sandbox-shell}/bin/busybox"
+  ] ++ lib.optional (doBuild && stdenv.isLinux && !(stdenv.hostPlatform.isStatic && stdenv.system == "aarch64-linux"))
+       "LDFLAGS=-fuse-ld=gold"
+    ++ lib.optional (doBuild && stdenv.hostPlatform.isStatic) "--enable-embedded-sandbox-shell"
+    ++ lib.optional buildUnitTests "RAPIDCHECK_HEADERS=${lib.getDev rapidcheck}/extras/gtest/include";
+
+  enableParallelBuilding = true;
+
+  makeFlags = "profiledir=$(out)/etc/profile.d PRECOMPILE_HEADERS=1";
+
+  installTargets = lib.optional doBuild "install"
+    ++ lib.optional enableInternalAPIDocs "internal-api-html";
+
+  installFlags = "sysconfdir=$(out)/etc";
+
+  # In this case we are probably just running tests, and so there isn't
+  # anything to install, we just make an empty directory to signify tests
+  # succeeded.
+  installPhase = if finalAttrs.installTargets != [] then null else ''
+    mkdir -p $out
+  '';
+
+  postInstall = lib.optionalString doBuild (
+    ''
+      mkdir -p $doc/nix-support
+      echo "doc manual $doc/share/doc/nix/manual" >> $doc/nix-support/hydra-build-products
+    '' + lib.optionalString stdenv.hostPlatform.isStatic ''
+      mkdir -p $out/nix-support
+      echo "file binary-dist $out/bin/nix" >> $out/nix-support/hydra-build-products
+    '' + lib.optionalString stdenv.isDarwin ''
+      install_name_tool \
+      -change ${boost}/lib/libboost_context.dylib \
+      $out/lib/libboost_context.dylib \
+      $out/lib/libnixutil.dylib
+    ''
+  ) + lib.optionalString enableInternalAPIDocs ''
+    mkdir -p ''${!outputDoc}/nix-support
+    echo "doc internal-api-docs $out/share/doc/nix/internal-api/html" >> ''${!outputDoc}/nix-support/hydra-build-products
+  '';
+
+  doInstallCheck = attrs.doInstallCheck;
+
+  installCheckFlags = "sysconfdir=$(out)/etc";
+  # Work around buggy detection in stdenv.
+  installCheckTarget = "installcheck";
+
+  # Work around weird bug where it doesn't think there is a Makefile.
+  installCheckPhase = if (!doBuild && doInstallCheck) then ''
+    mkdir -p src/nix-channel
+    make installcheck -j$NIX_BUILD_CORES -l$NIX_BUILD_CORES
+  '' else null;
+
+  # Needed for tests if we are not doing a build, but testing existing
+  # built Nix.
+  preInstallCheck = lib.optionalString (! doBuild) ''
+    mkdir -p src/nix-channel
+  '';
+
+  separateDebugInfo = !stdenv.hostPlatform.isStatic;
+
+  # TODO `releaseTools.coverageAnalysis` in Nixpkgs needs to be updated
+  # to work with `strictDeps`.
+  strictDeps = !withCoverageChecks;
+
+  hardeningDisable = lib.optional stdenv.hostPlatform.isStatic "pie";
+
+  meta = {
+    platforms = lib.platforms.unix ++ lib.platforms.windows;
+    mainProgram = "nix";
+    broken = !(lib.all (a: a) [
+      # We cannot run or install unit tests if we don't build them or
+      # Nix proper (which they depend on).
+      (installUnitTests -> doBuild)
+      (doCheck -> doBuild)
+      # We have to build the manual to build unreleased notes, as those
+      # are part of the manual
+      (buildUnreleasedNotes -> enableManual)
+      # The build process for the manual currently requires extracting
+      # data from the Nix executable we are trying to document.
+      (enableManual -> doBuild)
+    ]);
+  };
+
+} // lib.optionalAttrs withCoverageChecks {
+  lcovFilter = [ "*/boost/*" "*-tab.*" ];
+
+  hardeningDisable = ["fortify"];
+
+  NIX_CFLAGS_COMPILE = "-DCOVERAGE=1";
+
+  dontInstall = false;
+} // lib.optionalAttrs (test-daemon != null) {
+  NIX_DAEMON_PACKAGE = test-daemon;
+} // lib.optionalAttrs (test-client != null) {
+  NIX_CLIENT_PACKAGE = test-client;
+})
diff --git a/scripts/binary-tarball.nix b/scripts/binary-tarball.nix
new file mode 100644
index 000000000..104189b0c
--- /dev/null
+++ b/scripts/binary-tarball.nix
@@ -0,0 +1,84 @@
+{ runCommand
+, system
+, buildPackages
+, cacert
+, nix
+}:
+
+let
+
+  installerClosureInfo = buildPackages.closureInfo {
+    rootPaths = [ nix cacert ];
+  };
+
+  inherit (nix) version;
+
+  env = {
+    #nativeBuildInputs = lib.optional (system != "aarch64-linux") shellcheck;
+    meta.description = "Distribution-independent Nix bootstrap binaries for ${system}";
+  };
+
+in
+
+runCommand "nix-binary-tarball-${version}" env ''
+  cp ${installerClosureInfo}/registration $TMPDIR/reginfo
+  cp ${./create-darwin-volume.sh} $TMPDIR/create-darwin-volume.sh
+  substitute ${./install-nix-from-closure.sh} $TMPDIR/install \
+    --subst-var-by nix ${nix} \
+    --subst-var-by cacert ${cacert}
+
+  substitute ${./install-darwin-multi-user.sh} $TMPDIR/install-darwin-multi-user.sh \
+    --subst-var-by nix ${nix} \
+    --subst-var-by cacert ${cacert}
+  substitute ${./install-systemd-multi-user.sh} $TMPDIR/install-systemd-multi-user.sh \
+    --subst-var-by nix ${nix} \
+    --subst-var-by cacert ${cacert}
+  substitute ${./install-multi-user.sh} $TMPDIR/install-multi-user \
+    --subst-var-by nix ${nix} \
+    --subst-var-by cacert ${cacert}
+
+  if type -p shellcheck; then
+    # SC1090: Don't worry about not being able to find
+    #         $nix/etc/profile.d/nix.sh
+    shellcheck --exclude SC1090 $TMPDIR/install
+    shellcheck $TMPDIR/create-darwin-volume.sh
+    shellcheck $TMPDIR/install-darwin-multi-user.sh
+    shellcheck $TMPDIR/install-systemd-multi-user.sh
+
+    # SC1091: Don't panic about not being able to source
+    #         /etc/profile
+    # SC2002: Ignore "useless cat" "error", when loading
+    #         .reginfo, as the cat is a much cleaner
+    #         implementation, even though it is "useless"
+    # SC2116: Allow ROOT_HOME=$(echo ~root) for resolving
+    #         root's home directory
+    shellcheck --external-sources \
+      --exclude SC1091,SC2002,SC2116 $TMPDIR/install-multi-user
+  fi
+
+  chmod +x $TMPDIR/install
+  chmod +x $TMPDIR/create-darwin-volume.sh
+  chmod +x $TMPDIR/install-darwin-multi-user.sh
+  chmod +x $TMPDIR/install-systemd-multi-user.sh
+  chmod +x $TMPDIR/install-multi-user
+  dir=nix-${version}-${system}
+  fn=$out/$dir.tar.xz
+  mkdir -p $out/nix-support
+  echo "file binary-dist $fn" >> $out/nix-support/hydra-build-products
+  tar cvfJ $fn \
+    --owner=0 --group=0 --mode=u+rw,uga+r \
+    --mtime='1970-01-01' \
+    --absolute-names \
+    --hard-dereference \
+    --transform "s,$TMPDIR/install,$dir/install," \
+    --transform "s,$TMPDIR/create-darwin-volume.sh,$dir/create-darwin-volume.sh," \
+    --transform "s,$TMPDIR/reginfo,$dir/.reginfo," \
+    --transform "s,$NIX_STORE,$dir/store,S" \
+    $TMPDIR/install \
+    $TMPDIR/create-darwin-volume.sh \
+    $TMPDIR/install-darwin-multi-user.sh \
+    $TMPDIR/install-systemd-multi-user.sh \
+    $TMPDIR/install-multi-user \
+    $TMPDIR/reginfo \
+    $(cat ${installerClosureInfo}/store-paths)
+''
diff --git a/scripts/installer.nix b/scripts/installer.nix
new file mode 100644
index 000000000..cc7759c2c
--- /dev/null
+++ b/scripts/installer.nix
@@ -0,0 +1,36 @@
+{ lib
+, runCommand
+, nix
+, tarballs
+}:
+
+runCommand "installer-script" {
+  buildInputs = [ nix ];
+} ''
+  mkdir -p $out/nix-support
+
+  # Converts /nix/store/50p3qk8k...-nix-2.4pre20201102_550e11f/bin/nix to 50p3qk8k.../bin/nix.
+  tarballPath() {
+    # Remove the store prefix
+    local path=''${1#${builtins.storeDir}/}
+    # Get the path relative to the derivation root
+    local rest=''${path#*/}
+    # Get the derivation hash
+    local drvHash=''${path%%-*}
+    echo "$drvHash/$rest"
+  }
+
+  substitute ${./install.in} $out/install \
+    ${lib.concatMapStrings
+      (tarball: let
+          inherit (tarball.stdenv.hostPlatform) system;
+        in '' \
+        --replace '@tarballHash_${system}@' $(nix --experimental-features nix-command hash-file --base16 --type sha256 ${tarball}/*.tar.xz) \
+        --replace '@tarballPath_${system}@' $(tarballPath ${tarball}/*.tar.xz) \
+        ''
+      )
+      tarballs
+    } --replace '@nixVersion@' ${nix.version}
+
+  echo "file installer $out/install" >> $out/nix-support/hydra-build-products
+''