diff --git a/java/droidstubs.go b/java/droidstubs.go
index 12590ca..d9efb40 100644
--- a/java/droidstubs.go
+++ b/java/droidstubs.go
@@ -17,6 +17,7 @@
 import (
 	"fmt"
 	"path/filepath"
+	"regexp"
 	"strings"
 
 	"github.com/google/blueprint/proptools"
@@ -142,6 +143,10 @@
 	// if set to true, collect the values used by the Dev tools and
 	// write them in files packaged with the SDK. Defaults to false.
 	Write_sdk_values *bool
+
+	// path or filegroup to file defining extension an SDK name <-> numerical ID mapping and
+	// what APIs exist in which SDKs; passed to metalava via --sdk-extensions-info
+	Extensions_info_file *string `android:"path"`
 }
 
 // Used by xsd_config
@@ -398,9 +403,20 @@
 	filename := proptools.StringDefault(d.properties.Api_levels_jar_filename, "android.jar")
 
 	var dirs []string
+	var extensions_dir string
 	ctx.VisitDirectDepsWithTag(metalavaAPILevelsAnnotationsDirTag, func(m android.Module) {
 		if t, ok := m.(*ExportedDroiddocDir); ok {
+			extRegex := regexp.MustCompile(t.dir.String() + `/extensions/[0-9]+/public/.*\.jar`)
+
+			// Grab the first extensions_dir and we find while scanning ExportedDroiddocDir.deps;
+			// ideally this should be read from prebuiltApis.properties.Extensions_*
 			for _, dep := range t.deps {
+				if extRegex.MatchString(dep.String()) && d.properties.Extensions_info_file != nil {
+					if extensions_dir == "" {
+						extensions_dir = t.dir.String() + "/extensions"
+					}
+					cmd.Implicit(dep)
+				}
 				if dep.Base() == filename {
 					cmd.Implicit(dep)
 				}
@@ -445,6 +461,16 @@
 			cmd.FlagWithArg("--android-jar-pattern ", fmt.Sprintf("%s/%%/%s/%s", dir, sdkDir, filename))
 		}
 	}
+
+	if d.properties.Extensions_info_file != nil {
+		if extensions_dir == "" {
+			ctx.ModuleErrorf("extensions_info_file set, but no SDK extension dirs found")
+		}
+		info_file := android.PathForModuleSrc(ctx, *d.properties.Extensions_info_file)
+		cmd.Implicit(info_file)
+		cmd.FlagWithArg("--sdk-extensions-root ", extensions_dir)
+		cmd.FlagWithArg("--sdk-extensions-info ", info_file.String())
+	}
 }
 
 func metalavaUseRbe(ctx android.ModuleContext) bool {
diff --git a/java/droidstubs_test.go b/java/droidstubs_test.go
index 9fdfdde..2443692 100644
--- a/java/droidstubs_test.go
+++ b/java/droidstubs_test.go
@@ -259,3 +259,33 @@
 		t.Errorf("inputs of %q must be []string{%q}, but was %#v.", moduleName, systemJar, systemJars)
 	}
 }
+
+func TestDroidstubsWithSdkExtensions(t *testing.T) {
+	ctx, _ := testJavaWithFS(t, `
+		droiddoc_exported_dir {
+			name: "sdk-dir",
+			path: "sdk",
+		}
+
+		droidstubs {
+			name: "baz-stubs",
+			api_levels_annotations_dirs: ["sdk-dir"],
+			api_levels_annotations_enabled: true,
+			extensions_info_file: ":info-file",
+		}
+
+		filegroup {
+			name: "info-file",
+			srcs: ["sdk/extensions/info.txt"],
+		}
+		`,
+		map[string][]byte{
+			"sdk/extensions/1/public/some-mainline-module-stubs.jar": nil,
+			"sdk/extensions/info.txt":                                nil,
+		})
+	m := ctx.ModuleForTests("baz-stubs", "android_common")
+	manifest := m.Output("metalava.sbox.textproto")
+	cmdline := String(android.RuleBuilderSboxProtoForTests(t, manifest).Commands[0].Command)
+	android.AssertStringDoesContain(t, "sdk-extensions-root present", cmdline, "--sdk-extensions-root sdk/extensions")
+	android.AssertStringDoesContain(t, "sdk-extensions-info present", cmdline, "--sdk-extensions-info sdk/extensions/info.txt")
+}