diff --git a/sdk/sdk.go b/sdk/sdk.go
index fcb3fb7..d122cda 100644
--- a/sdk/sdk.go
+++ b/sdk/sdk.go
@@ -15,6 +15,9 @@
 package sdk
 
 import (
+	"fmt"
+	"strconv"
+
 	"github.com/google/blueprint"
 
 	"android/soong/android"
@@ -25,6 +28,7 @@
 
 func init() {
 	android.RegisterModuleType("sdk", ModuleFactory)
+	android.RegisterModuleType("sdk_snapshot", SnapshotModuleFactory)
 	android.PreDepsMutators(RegisterPreDepsMutators)
 	android.PostDepsMutators(RegisterPostDepsMutators)
 }
@@ -34,12 +38,18 @@
 	android.DefaultableModuleBase
 
 	properties sdkProperties
+
+	updateScript android.OutputPath
+	freezeScript android.OutputPath
 }
 
 type sdkProperties struct {
-	// The list of java_import modules that provide Java stubs for this SDK
-	Java_libs          []string
+	// The list of java libraries in this SDK
+	Java_libs []string
+	// The list of native libraries in this SDK
 	Native_shared_libs []string
+
+	Snapshot bool `blueprint:"mutated"`
 }
 
 // sdk defines an SDK which is a logical group of modules (e.g. native libs, headers, java libs, etc.)
@@ -52,8 +62,44 @@
 	return s
 }
 
+// sdk_snapshot is a versioned snapshot of an SDK. This is an auto-generated module.
+func SnapshotModuleFactory() android.Module {
+	s := ModuleFactory()
+	s.(*sdk).properties.Snapshot = true
+	return s
+}
+
+func (s *sdk) snapshot() bool {
+	return s.properties.Snapshot
+}
+
+func (s *sdk) frozenVersions(ctx android.BaseModuleContext) []string {
+	if s.snapshot() {
+		panic(fmt.Errorf("frozenVersions() called for sdk_snapshot %q", ctx.ModuleName()))
+	}
+	versions := []string{}
+	ctx.WalkDeps(func(child android.Module, parent android.Module) bool {
+		depTag := ctx.OtherModuleDependencyTag(child)
+		if depTag == sdkMemberDepTag {
+			return true
+		}
+		if versionedDepTag, ok := depTag.(sdkMemberVesionedDepTag); ok {
+			v := versionedDepTag.version
+			if v != "current" && !android.InList(v, versions) {
+				versions = append(versions, versionedDepTag.version)
+			}
+		}
+		return false
+	})
+	return android.SortedUniqueStrings(versions)
+}
+
 func (s *sdk) GenerateAndroidBuildActions(ctx android.ModuleContext) {
-	// TODO(jiyong): add build rules for creating stubs from members of this SDK
+	s.buildSnapshotGenerationScripts(ctx)
+}
+
+func (s *sdk) AndroidMkEntries() android.AndroidMkEntries {
+	return s.androidMkEntriesForScript()
 }
 
 // RegisterPreDepsMutators registers pre-deps mutators to support modules implementing SdkAware
@@ -112,8 +158,21 @@
 
 // Step 2: record that dependencies of SDK modules are members of the SDK modules
 func memberDepsMutator(mctx android.TopDownMutatorContext) {
-	if _, ok := mctx.Module().(*sdk); ok {
+	if s, ok := mctx.Module().(*sdk); ok {
 		mySdkRef := android.ParseSdkRef(mctx, mctx.ModuleName(), "name")
+		if s.snapshot() && mySdkRef.Unversioned() {
+			mctx.PropertyErrorf("name", "sdk_snapshot should be named as <name>@<version>. "+
+				"Did you manually modify Android.bp?")
+		}
+		if !s.snapshot() && !mySdkRef.Unversioned() {
+			mctx.PropertyErrorf("name", "sdk shouldn't be named as <name>@<version>.")
+		}
+		if mySdkRef.Version != "" && mySdkRef.Version != "current" {
+			if _, err := strconv.Atoi(mySdkRef.Version); err != nil {
+				mctx.PropertyErrorf("name", "version %q is neither a number nor \"current\"", mySdkRef.Version)
+			}
+		}
+
 		mctx.VisitDirectDeps(func(child android.Module) {
 			if member, ok := child.(android.SdkAware); ok {
 				member.MakeMemberOf(mySdkRef)
@@ -122,7 +181,7 @@
 	}
 }
 
-// Step 3: create dependencies from the in-development version of an SDK member to frozen versions
+// Step 3: create dependencies from the unversioned SDK member to snapshot versions
 // of the same member. By having these dependencies, they are mutated for multiple Mainline modules
 // (apex and apk), each of which might want different sdks to be built with. For example, if both
 // apex A and B are referencing libfoo which is a member of sdk 'mysdk', the two APEXes can be
@@ -130,7 +189,7 @@
 // using.
 func memberInterVersionMutator(mctx android.BottomUpMutatorContext) {
 	if m, ok := mctx.Module().(android.SdkAware); ok && m.IsInAnySdk() {
-		if !m.ContainingSdk().IsCurrentVersion() {
+		if !m.ContainingSdk().Unversioned() {
 			memberName := m.MemberName()
 			tag := sdkMemberVesionedDepTag{member: memberName, version: m.ContainingSdk().Version}
 			mctx.AddReverseDependency(mctx.Module(), tag, memberName)
@@ -159,7 +218,7 @@
 // versioned module is used instead of the un-versioned (in-development) module libfoo
 func sdkDepsReplaceMutator(mctx android.BottomUpMutatorContext) {
 	if m, ok := mctx.Module().(android.SdkAware); ok && m.IsInAnySdk() {
-		if sdk := m.ContainingSdk(); !sdk.IsCurrentVersion() {
+		if sdk := m.ContainingSdk(); !sdk.Unversioned() {
 			if m.RequiredSdks().Contains(sdk) {
 				// Note that this replacement is done only for the modules that have the same
 				// variations as the current module. Since current module is already mutated for