diff --git a/cc/config/clang.go b/cc/config/clang.go
index 5cf2421..b58223f 100644
--- a/cc/config/clang.go
+++ b/cc/config/clang.go
@@ -92,12 +92,7 @@
 	"-Wl,-m,aarch64_elf64_le_vec",
 })
 
-var ClangLibToolingUnknownCflags = []string{
-	// Remove -flto and other flto dependent flags.
-	"-flto*",
-	"-fsanitize*",
-	"-fwhole-program-vtables",
-}
+var ClangLibToolingUnknownCflags []string = nil
 
 func init() {
 	pctx.StaticVariable("ClangExtraCflags", strings.Join([]string{
diff --git a/cc/sabi.go b/cc/sabi.go
index 72a3c5c..4a86499 100644
--- a/cc/sabi.go
+++ b/cc/sabi.go
@@ -73,17 +73,6 @@
 	flags.ToolingCFlags = filterOutWithPrefix(flags.CFlags, config.ClangLibToolingUnknownCflags)
 	flags.ToolingCppFlags = filterOutWithPrefix(flags.CppFlags, config.ClangLibToolingUnknownCflags)
 
-	// RSClang does not support recent mcpu option likes exynos-m2.
-	// So we need overriding mcpu option when we want to use it.
-	mappedArch := map[string]string{
-		"exynos-m2":  "cortex-a53",
-		"cortex-a55": "cortex-a53",
-		"cortex-a75": "cortex-a57",
-	}
-	if arch, ok := mappedArch[ctx.Arch().CpuVariant]; ok {
-		flags.ToolingCFlags = append(flags.ToolingCFlags, "-mcpu="+arch)
-	}
-
 	return flags
 }
 
diff --git a/cc/vndk.go b/cc/vndk.go
index 5a24a98..1a9b77a 100644
--- a/cc/vndk.go
+++ b/cc/vndk.go
@@ -15,6 +15,7 @@
 package cc
 
 import (
+	"errors"
 	"sort"
 	"strings"
 	"sync"
@@ -151,38 +152,42 @@
 	}
 
 	// Check the dependencies of VNDK shared libraries.
-	if !vndkIsVndkDepAllowed(vndk, to.vndkdep) {
-		ctx.ModuleErrorf("(%s) should not link to %q (%s)",
-			vndk.typeName(), to.Name(), to.vndkdep.typeName())
+	if err := vndkIsVndkDepAllowed(vndk, to.vndkdep); err != nil {
+		ctx.ModuleErrorf("(%s) should not link to %q (%s): %v",
+			vndk.typeName(), to.Name(), to.vndkdep.typeName(), err)
 		return
 	}
 }
 
-func vndkIsVndkDepAllowed(from *vndkdep, to *vndkdep) bool {
+func vndkIsVndkDepAllowed(from *vndkdep, to *vndkdep) error {
 	// Check the dependencies of VNDK, VNDK-Ext, VNDK-SP, VNDK-SP-Ext and vendor modules.
 	if from.isVndkExt() {
 		if from.isVndkSp() {
-			// VNDK-SP-Ext may depend on VNDK-SP, VNDK-SP-Ext, or vendor libs (excluding
-			// VNDK and VNDK-Ext).
-			return to.isVndkSp() || !to.isVndk()
+			if to.isVndk() && !to.isVndkSp() {
+				return errors.New("VNDK-SP extensions must not depend on VNDK or VNDK extensions")
+			}
+			return nil
 		}
 		// VNDK-Ext may depend on VNDK, VNDK-Ext, VNDK-SP, VNDK-SP-Ext, or vendor libs.
-		return true
+		return nil
 	}
 	if from.isVndk() {
 		if to.isVndkExt() {
-			// VNDK-core and VNDK-SP must not depend on VNDK extensions.
-			return false
+			return errors.New("VNDK-core and VNDK-SP must not depend on VNDK extensions")
 		}
 		if from.isVndkSp() {
-			// VNDK-SP must only depend on VNDK-SP.
-			return to.isVndkSp()
+			if !to.isVndkSp() {
+				return errors.New("VNDK-SP must only depend on VNDK-SP")
+			}
+			return nil
 		}
-		// VNDK-core may depend on VNDK-core or VNDK-SP.
-		return to.isVndk()
+		if !to.isVndk() {
+			return errors.New("VNDK-core must only depend on VNDK-core or VNDK-SP")
+		}
+		return nil
 	}
 	// Vendor modules may depend on VNDK, VNDK-Ext, VNDK-SP, VNDK-SP-Ext, or vendor libs.
-	return true
+	return nil
 }
 
 var (
diff --git a/java/config/config.go b/java/config/config.go
index 85cb588..d2a8c46 100644
--- a/java/config/config.go
+++ b/java/config/config.go
@@ -27,8 +27,8 @@
 var (
 	pctx = android.NewPackageContext("android/soong/java/config")
 
-	DefaultBootclasspathLibraries = []string{"core-oj", "core-libart", "core-simple", "bouncycastle", "conscrypt", "okhttp"}
-	DefaultSystemModules          = "core-system-modules"
+	DefaultBootclasspathLibraries = []string{"core.platform.api.stubs", "core-lambda-stubs"}
+	DefaultSystemModules          = "core-platform-api-stubs-system-modules"
 	DefaultLibraries              = []string{"ext", "framework"}
 	DefaultLambdaStubsLibrary     = "core-lambda-stubs"
 	SdkLambdaStubsPath            = "prebuilts/sdk/tools/core-lambda-stubs.jar"
diff --git a/java/java_test.go b/java/java_test.go
index 76244f0..2de2778 100644
--- a/java/java_test.go
+++ b/java/java_test.go
@@ -124,6 +124,7 @@
 		"android_system_stubs_current",
 		"android_test_stubs_current",
 		"core.current.stubs",
+		"core.platform.api.stubs",
 		"kotlin-stdlib",
 	}
 
@@ -134,7 +135,7 @@
 				srcs: ["a.java"],
 				no_standard_libs: true,
 				sdk_version: "core_current",
-				system_modules: "core-system-modules",
+				system_modules: "core-platform-api-stubs-system-modules",
 			}
 		`, extra)
 	}
@@ -148,6 +149,7 @@
 
 	systemModules := []string{
 		"core-system-modules",
+		"core-platform-api-stubs-system-modules",
 		"android_stubs_current_system_modules",
 		"android_system_stubs_current_system_modules",
 		"android_test_stubs_current_system_modules",
@@ -367,15 +369,15 @@
 }{
 	{
 		name:          "default",
-		bootclasspath: []string{"core-oj", "core-libart", "core-simple", "bouncycastle", "conscrypt", "okhttp"},
-		system:        "core-system-modules",
+		bootclasspath: []string{"core.platform.api.stubs", "core-lambda-stubs"},
+		system:        "core-platform-api-stubs-system-modules",
 		classpath:     []string{"ext", "framework"},
 	},
 	{
 		name:          "blank sdk version",
 		properties:    `sdk_version: "",`,
-		bootclasspath: []string{"core-oj", "core-libart", "core-simple", "bouncycastle", "conscrypt", "okhttp"},
-		system:        "core-system-modules",
+		bootclasspath: []string{"core.platform.api.stubs", "core-lambda-stubs"},
+		system:        "core-platform-api-stubs-system-modules",
 		classpath:     []string{"ext", "framework"},
 	},
 	{
@@ -433,8 +435,8 @@
 	{
 
 		name:          "nostdlib system_modules",
-		properties:    `no_standard_libs: true, system_modules: "core-system-modules"`,
-		system:        "core-system-modules",
+		properties:    `no_standard_libs: true, system_modules: "core-platform-api-stubs-system-modules"`,
+		system:        "core-platform-api-stubs-system-modules",
 		bootclasspath: []string{`""`},
 		classpath:     []string{},
 	},
diff --git a/python/scripts/stub_template_host.txt b/python/scripts/stub_template_host.txt
index e686211..213401d 100644
--- a/python/scripts/stub_template_host.txt
+++ b/python/scripts/stub_template_host.txt
@@ -41,6 +41,7 @@
   args = sys.argv[1:]
 
   new_env = {}
+  runfiles_path = None
 
   try:
     runfiles_path = ExtractRunfiles()
@@ -82,7 +83,8 @@
   except:
     raise
   finally:
-    shutil.rmtree(runfiles_path, True)
+    if runfiles_path is not None:
+      shutil.rmtree(runfiles_path, True)
 
 if __name__ == '__main__':
   Main()
diff --git a/scripts/manifest_fixer.py b/scripts/manifest_fixer.py
index 05bd66e..9256cb2 100755
--- a/scripts/manifest_fixer.py
+++ b/scripts/manifest_fixer.py
@@ -56,7 +56,9 @@
   parser.add_argument('--library', dest='library', action='store_true',
                       help='manifest is for a static library')
   parser.add_argument('--uses-library', dest='uses_libraries', action='append',
-                      help='specify additional <uses-library> tag to add')
+                      help='specify additional <uses-library> tag to add. android:requred is set to true')
+  parser.add_argument('--optional-uses-library', dest='optional_uses_libraries', action='append',
+                      help='specify additional <uses-library> tag to add. android:requred is set to false')
   parser.add_argument('--uses-non-sdk-api', dest='uses_non_sdk_api', action='store_true',
                       help='manifest is for a package built against the platform')
   parser.add_argument('input', help='input AndroidManifest.xml file')
@@ -190,12 +192,13 @@
     element.setAttributeNode(target_attr)
 
 
-def add_uses_libraries(doc, new_uses_libraries):
-  """Add additional <uses-library> tags with android:required=false.
+def add_uses_libraries(doc, new_uses_libraries, required):
+  """Add additional <uses-library> tags
 
   Args:
     doc: The XML document. May be modified by this function.
     new_uses_libraries: The names of libraries to be added by this function.
+    required: The value of android:required attribute. Can be true or false.
   Raises:
     RuntimeError: Invalid manifest
   """
@@ -227,7 +230,7 @@
 
     ul = doc.createElement('uses-library')
     ul.setAttributeNS(android_ns, 'android:name', name)
-    ul.setAttributeNS(android_ns, 'android:required', 'false')
+    ul.setAttributeNS(android_ns, 'android:required', str(required).lower())
 
     application.insertBefore(doc.createTextNode(indent), last)
     application.insertBefore(ul, last)
@@ -285,7 +288,10 @@
       raise_min_sdk_version(doc, args.min_sdk_version, args.target_sdk_version, args.library)
 
     if args.uses_libraries:
-      add_uses_libraries(doc, args.uses_libraries)
+      add_uses_libraries(doc, args.uses_libraries, True)
+
+    if args.optional_uses_libraries:
+      add_uses_libraries(doc, args.optional_uses_libraries, False)
 
     if args.uses_non_sdk_api:
       add_uses_non_sdk_api(doc)