diff --git a/apex/platform_bootclasspath_test.go b/apex/platform_bootclasspath_test.go
index bd4a9d5..bc35479 100644
--- a/apex/platform_bootclasspath_test.go
+++ b/apex/platform_bootclasspath_test.go
@@ -398,6 +398,7 @@
 			name: "foo",
 			prefer: false,
 			shared_library: false,
+			permitted_packages: ["foo"],
 			public: {
 				jars: ["sdk_library/public/foo-stubs.jar"],
 				stub_srcs: ["sdk_library/public/foo_stub_sources"],
diff --git a/cmd/soong_ui/main.go b/cmd/soong_ui/main.go
index 22922c0..8bcc712 100644
--- a/cmd/soong_ui/main.go
+++ b/cmd/soong_ui/main.go
@@ -16,6 +16,7 @@
 
 import (
 	"context"
+	"encoding/json"
 	"flag"
 	"fmt"
 	"io/ioutil"
@@ -34,6 +35,11 @@
 	"android/soong/ui/tracer"
 )
 
+const (
+	configDir  = "vendor/google/tools/soong_config"
+	jsonSuffix = "json"
+)
+
 // A command represents an operation to be executed in the soong build
 // system.
 type command struct {
@@ -110,6 +116,34 @@
 	return indexList(s, list) != -1
 }
 
+func loadEnvConfig() error {
+	bc := os.Getenv("ANDROID_BUILD_ENVIRONMENT_CONFIG")
+	if bc == "" {
+		return nil
+	}
+	cfgFile := filepath.Join(os.Getenv("TOP"), configDir, fmt.Sprintf("%s.%s", bc, jsonSuffix))
+
+	envVarsJSON, err := ioutil.ReadFile(cfgFile)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "\033[33mWARNING:\033[0m failed to open config file %s: %s\n", cfgFile, err.Error())
+		return nil
+	}
+
+	var envVars map[string]map[string]string
+	if err := json.Unmarshal(envVarsJSON, &envVars); err != nil {
+		return fmt.Errorf("env vars config file: %s did not parse correctly: %s", cfgFile, err.Error())
+	}
+	for k, v := range envVars["env"] {
+		if os.Getenv(k) != "" {
+			continue
+		}
+		if err := os.Setenv(k, v); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 // Main execution of soong_ui. The command format is as follows:
 //
 //    soong_ui <command> [<arg 1> <arg 2> ... <arg n>]
@@ -173,6 +207,12 @@
 
 	config := c.config(buildCtx, args...)
 
+	if err := loadEnvConfig(); err != nil {
+		fmt.Fprintf(os.Stderr, "failed to parse env config files: %v", err)
+		os.Exit(1)
+	}
+
+
 	build.SetupOutDir(buildCtx, config)
 
 	if config.UseBazel() && config.Dist() {
diff --git a/java/java.go b/java/java.go
index 727cef5..bbed42d 100644
--- a/java/java.go
+++ b/java/java.go
@@ -1192,6 +1192,12 @@
 	minSdkVersion android.SdkSpec
 }
 
+var _ PermittedPackagesForUpdatableBootJars = (*Import)(nil)
+
+func (j *Import) PermittedPackagesForUpdatableBootJars() []string {
+	return j.properties.Permitted_packages
+}
+
 func (j *Import) SdkVersion(ctx android.EarlyModuleContext) android.SdkSpec {
 	return android.SdkSpecFrom(ctx, String(j.properties.Sdk_version))
 }
diff --git a/java/sdk_library.go b/java/sdk_library.go
index c0e5662..8c66438 100644
--- a/java/sdk_library.go
+++ b/java/sdk_library.go
@@ -1991,6 +1991,12 @@
 	return module
 }
 
+var _ PermittedPackagesForUpdatableBootJars = (*SdkLibraryImport)(nil)
+
+func (module *SdkLibraryImport) PermittedPackagesForUpdatableBootJars() []string {
+	return module.properties.Permitted_packages
+}
+
 func (module *SdkLibraryImport) Prebuilt() *android.Prebuilt {
 	return &module.prebuilt
 }
diff --git a/sdk/bootclasspath_fragment_sdk_test.go b/sdk/bootclasspath_fragment_sdk_test.go
index c30324a..412e806 100644
--- a/sdk/bootclasspath_fragment_sdk_test.go
+++ b/sdk/bootclasspath_fragment_sdk_test.go
@@ -532,6 +532,12 @@
 				out/soong/.intermediates/frameworks/base/boot/platform-bootclasspath/android_common/hiddenapi-monolithic/index-from-classes.csv
         snapshot/hiddenapi/index.csv
 			`, rule)
+
+			// Make sure that the permitted packages from the prebuilts end up in the
+			// updatable-bcp-packages.txt file.
+			rule = module.Output("updatable-bcp-packages.txt")
+			expectedContents := `'mybootlib\nmyothersdklibrary\n'`
+			android.AssertStringEquals(t, "updatable-bcp-packages.txt", expectedContents, rule.Args["content"])
 		}),
 		snapshotTestPreparer(checkSnapshotWithSourcePreferred, preparerForSnapshot),
 		snapshotTestPreparer(checkSnapshotPreferredWithSource, preparerForSnapshot),