diff --git a/cmd/mbf/main.go b/cmd/mbf/main.go
index e593c33b..c69ba0a6 100644
--- a/cmd/mbf/main.go
+++ b/cmd/mbf/main.go
@@ -396,24 +396,27 @@ func main() {
 					rosa.SetGentooStage3(flagGentoo, checksum)
 				}
 
-				_, stage1 := (t - 2).NewLLVM()
-				_, stage2 := (t - 1).NewLLVM()
-				_, stage3 := t.NewLLVM()
 				var (
 					pathname *check.Absolute
 					checksum [2]unique.Handle[pkg.Checksum]
 				)
 
-				if pathname, _, err = cache.Cure(stage1); err != nil {
+				if pathname, _, err = cache.Cure(
+					(t - 2).Load(rosa.LLVMClang),
+				); err != nil {
 					return err
 				}
 				log.Println("stage1:", pathname)
 
-				if pathname, checksum[0], err = cache.Cure(stage2); err != nil {
+				if pathname, checksum[0], err = cache.Cure(
+					(t - 1).Load(rosa.LLVMClang),
+				); err != nil {
 					return err
 				}
 				log.Println("stage2:", pathname)
-				if pathname, checksum[1], err = cache.Cure(stage3); err != nil {
+				if pathname, checksum[1], err = cache.Cure(
+					t.Load(rosa.LLVMClang),
+				); err != nil {
 					return err
 				}
 				log.Println("stage3:", pathname)
@@ -565,7 +568,7 @@ func main() {
 			"shell",
 			"Interactive shell in the specified Rosa OS environment",
 			func(args []string) error {
-				presets := make([]rosa.PArtifact, len(args))
+				presets := make([]rosa.PArtifact, len(args)+3)
 				for i, arg := range args {
 					p, ok := rosa.ResolveName(arg)
 					if !ok {
@@ -573,25 +576,20 @@ func main() {
 					}
 					presets[i] = p
 				}
+
+				base := rosa.LLVMClang
+				if !flagWithToolchain {
+					base = rosa.Musl
+				}
+				presets = append(presets,
+					base,
+					rosa.Mksh,
+					rosa.Toybox,
+				)
+
 				root := make(pkg.Collect, 0, 6+len(args))
 				root = rosa.Std.AppendPresets(root, presets...)
 
-				if flagWithToolchain {
-					boot := rosa.Std - 1
-					runtimes, clang := boot.NewLLVM()
-					root = append(root,
-						boot.Load(rosa.Musl),
-						boot.Load(rosa.LLVMCompilerRT),
-						runtimes, clang,
-					)
-				} else {
-					root = append(root, rosa.Std.Load(rosa.Musl))
-				}
-				root = append(root,
-					rosa.Std.Load(rosa.Mksh),
-					rosa.Std.Load(rosa.Toybox),
-				)
-
 				if _, _, err := cache.Cure(&root); err == nil {
 					return errors.New("unreachable")
 				} else if !pkg.IsCollected(err) {
diff --git a/internal/rosa/llvm.go b/internal/rosa/llvm.go
index 18db52a2..74d0cdc9 100644
--- a/internal/rosa/llvm.go
+++ b/internal/rosa/llvm.go
@@ -3,7 +3,6 @@ package rosa
 import (
 	"runtime"
 	"slices"
-	"sync"
 
 	"hakurei.app/internal/pkg"
 )
@@ -130,40 +129,26 @@ func init() {
 		Name:        "llvm-compiler-rt",
 		Description: "LLVM runtime: compiler-rt",
 		Website:     "https://llvm.org/",
+
+		Dependencies: P{
+			Musl,
+		},
 	}
 }
 
-// newLLVM returns LLVM toolchain across multiple [pkg.Artifact].
-func (t Toolchain) newLLVM() (runtimes, clang pkg.Artifact) {
-	target := "'AArch64;RISCV;X86'"
-	if t.isStage0() {
-		switch runtime.GOARCH {
-		case "386", "amd64":
-			target = "X86"
-		case "arm64":
-			target = "AArch64"
-		case "riscv64":
-			target = "RISCV"
-
-		default:
-			panic("unsupported target " + runtime.GOARCH)
-		}
-	}
-
-	minimalDeps := []KV{
-		{"LLVM_ENABLE_ZLIB", "OFF"},
-		{"LLVM_ENABLE_ZSTD", "OFF"},
-		{"LLVM_ENABLE_LIBXML2", "OFF"},
-	}
-
-	compilerRT := t.Load(LLVMCompilerRT)
-	musl := t.Load(Musl)
-
-	runtimes = t.newLLVMVariant("runtimes", &llvmAttr{
-		env: stage0ExclConcat(t, []string{},
+func (t Toolchain) newLLVMRuntimes() (pkg.Artifact, string) {
+	return t.NewPackage("llvm", llvmVersion, llvmSource, &PackageAttr{
+		Patches:   llvmPatches,
+		NonStage0: t.AppendPresets(nil, LLVMCompilerRT),
+		Env: stage0ExclConcat(t, []string{},
 			"LDFLAGS="+earlyLDFLAGS(false),
 		),
-		cmake: slices.Concat([]KV{
+		Flag: TExclusive,
+	}, &CMakeHelper{
+		Variant: "runtimes",
+		Append:  []string{"runtimes"},
+
+		Cache: []KV{
 			{"CMAKE_BUILD_TYPE", "Release"},
 
 			{"LLVM_HOST_TRIPLE", `"${ROSA_TRIPLE}"`},
@@ -181,21 +166,61 @@ func (t Toolchain) newLLVM() (runtimes, clang pkg.Artifact) {
 
 			{"LIBCXX_HAS_ATOMIC_LIB", "OFF"},
 			{"LIBCXXABI_HAS_CXA_THREAD_ATEXIT_IMPL", "OFF"},
-		}, minimalDeps),
-		append: []string{"runtimes"},
-		nonStage0: []pkg.Artifact{
-			compilerRT,
-			musl,
-		},
-	})
 
-	clang = t.newLLVMVariant("clang", &llvmAttr{
-		env: stage0ExclConcat(t, []string{},
+			{"LLVM_ENABLE_ZLIB", "OFF"},
+			{"LLVM_ENABLE_ZSTD", "OFF"},
+			{"LLVM_ENABLE_LIBXML2", "OFF"},
+		},
+	},
+		Python,
+
+		KernelHeaders,
+	), llvmVersion
+}
+func init() {
+	artifactsM[LLVMRuntimes] = Metadata{
+		f: Toolchain.newLLVMRuntimes,
+
+		Name:        "llvm-runtimes",
+		Description: "LLVM runtimes: libunwind, libcxx, libcxxabi",
+		Website:     "https://llvm.org/",
+
+		Dependencies: P{
+			LLVMCompilerRT,
+		},
+	}
+}
+
+func (t Toolchain) newLLVMClang() (pkg.Artifact, string) {
+	target := "'AArch64;RISCV;X86'"
+	if t.isStage0() {
+		switch runtime.GOARCH {
+		case "386", "amd64":
+			target = "X86"
+		case "arm64":
+			target = "AArch64"
+		case "riscv64":
+			target = "RISCV"
+
+		default:
+			panic("unsupported target " + runtime.GOARCH)
+		}
+	}
+
+	return t.NewPackage("llvm", llvmVersion, llvmSource, &PackageAttr{
+		Patches:   llvmPatches,
+		NonStage0: t.AppendPresets(nil, LLVMRuntimes),
+		Env: stage0ExclConcat(t, []string{},
 			"CFLAGS="+earlyCFLAGS,
 			"CXXFLAGS="+earlyCXXFLAGS(),
 			"LDFLAGS="+earlyLDFLAGS(false),
 		),
-		cmake: slices.Concat([]KV{
+		Flag: TExclusive,
+	}, &CMakeHelper{
+		Variant: "clang",
+		Append:  []string{"llvm"},
+
+		Cache: []KV{
 			{"CMAKE_BUILD_TYPE", "Release"},
 
 			{"LLVM_HOST_TRIPLE", `"${ROSA_TRIPLE}"`},
@@ -218,13 +243,12 @@ func (t Toolchain) newLLVM() (runtimes, clang pkg.Artifact) {
 			{"LLVM_TARGETS_TO_BUILD", target},
 			{"CMAKE_CROSSCOMPILING", "OFF"},
 			{"CXX_SUPPORTS_CUSTOM_LINKER", "ON"},
-		}, minimalDeps),
-		nonStage0: []pkg.Artifact{
-			musl,
-			compilerRT,
-			runtimes,
+
+			{"LLVM_ENABLE_ZLIB", "OFF"},
+			{"LLVM_ENABLE_ZSTD", "OFF"},
+			{"LLVM_ENABLE_LIBXML2", "OFF"},
 		},
-		script: `
+		Script: `
 ln -s ld.lld /work/system/bin/ld
 
 ln -s clang /work/system/bin/cc
@@ -232,32 +256,30 @@ ln -s clang++ /work/system/bin/c++
 
 ninja check-all
 `,
-	})
+	},
+		Python,
+		Perl,
+		Diffutils,
+		Bash,
+		Gawk,
+		Coreutils,
+		Findutils,
 
-	return
+		KernelHeaders,
+	), llvmVersion
 }
 func init() {
-	artifactsM[LLVMRuntimes] = Metadata{
-		f: func(t Toolchain) (pkg.Artifact, string) {
-			runtimes, _ := t.newLLVM()
-			return runtimes, llvmVersion
-		},
-
-		Name:        "llvm-runtimes",
-		Description: "LLVM runtimes: libunwind, libcxx, libcxxabi",
-		Website:     "https://llvm.org/",
-	}
-
 	artifactsM[LLVMClang] = Metadata{
-		f: func(t Toolchain) (pkg.Artifact, string) {
-			_, clang := t.newLLVM()
-			return clang, llvmVersion
-		},
+		f: Toolchain.newLLVMClang,
 
 		Name:        "clang",
 		Description: `an "LLVM native" C/C++/Objective-C compiler`,
 		Website:     "https://llvm.org/",
 
+		Dependencies: P{
+			LLVMRuntimes,
+		},
+
 		ID: 1830,
 	}
 
@@ -282,18 +304,3 @@ func init() {
 		Website:     "https://libclc.llvm.org/",
 	}
 }
-
-var (
-	// llvm stores the result of Toolchain.newLLVM.
-	llvm [_toolchainEnd][2]pkg.Artifact
-	// llvmOnce is for lazy initialisation of llvm.
-	llvmOnce [_toolchainEnd]sync.Once
-)
-
-// NewLLVM returns LLVM toolchain across multiple [pkg.Artifact].
-func (t Toolchain) NewLLVM() (runtimes, clang pkg.Artifact) {
-	llvmOnce[t].Do(func() {
-		llvm[t][0], llvm[t][1] = t.newLLVM()
-	})
-	return llvm[t][0], llvm[t][1]
-}
diff --git a/internal/rosa/rosa.go b/internal/rosa/rosa.go
index b2ae683b..8e6d6063 100644
--- a/internal/rosa/rosa.go
+++ b/internal/rosa/rosa.go
@@ -328,24 +328,23 @@ mkdir -vp /work/system/bin
 			name += "-std"
 		}
 
-		boot := t - 1
-		runtimes, clang := boot.NewLLVM()
 		toybox := Toybox
 		if flag&TEarly != 0 {
 			toybox = toyboxEarly
 		}
-		std := []pkg.Artifact{cureEtc{newIANAEtc()}, boot.Load(Musl)}
-		toolchain := []pkg.Artifact{boot.Load(LLVMCompilerRT), runtimes, clang}
-		utils := []pkg.Artifact{
-			boot.Load(Mksh),
-			boot.Load(toybox),
-		}
 
+		base := LLVMClang
 		if flag&TNoToolchain != 0 {
-			toolchain = nil
+			base = Musl
 		}
 
-		support = slices.Concat(extra, std, toolchain, utils)
+		support = slices.Concat(extra, (t-1).AppendPresets([]pkg.Artifact{
+			cureEtc{newIANAEtc()},
+		},
+			base,
+			Mksh,
+			toybox,
+		))
 		env = fixupEnviron(env, []string{
 			EnvTriplet + "=" + triplet(),
 			lcMessages,
diff --git a/internal/rosa/stage0.go b/internal/rosa/stage0.go
index d147440e..f4a2edc5 100644
--- a/internal/rosa/stage0.go
+++ b/internal/rosa/stage0.go
@@ -7,12 +7,11 @@ import (
 )
 
 func (t Toolchain) newStage0() (pkg.Artifact, string) {
-	runtimes, clang := t.NewLLVM()
 	return t.New("rosa-stage0", 0, []pkg.Artifact{
 		t.Load(Musl),
 		t.Load(LLVMCompilerRT),
-		runtimes,
-		clang,
+		t.Load(LLVMRuntimes),
+		t.Load(LLVMClang),
 
 		t.Load(Zlib),
 		t.Load(Bzip2),