diff --git a/cc/androidmk.go b/cc/androidmk.go
index 065d0aa..44e977f 100644
--- a/cc/androidmk.go
+++ b/cc/androidmk.go
@@ -318,7 +318,7 @@
 	ret.Class = "SHARED_LIBRARIES"
 
 	ret.Extra = append(ret.Extra, func(w io.Writer, outputFile android.Path) {
-		path, file := filepath.Split(c.installPath)
+		path, file := filepath.Split(c.installPath.String())
 		stem := strings.TrimSuffix(file, filepath.Ext(file))
 		fmt.Fprintln(w, "LOCAL_SYSTEM_SHARED_LIBRARIES :=")
 		fmt.Fprintln(w, "LOCAL_MODULE_SUFFIX := "+outputFile.Ext())
diff --git a/cc/cmakelists.go b/cc/cmakelists.go
index 13a2e8e..9b32182 100644
--- a/cc/cmakelists.go
+++ b/cc/cmakelists.go
@@ -23,8 +23,6 @@
 	"path"
 	"path/filepath"
 	"strings"
-
-	"github.com/google/blueprint"
 )
 
 // This singleton generates CMakeLists.txt files. It does so for each blueprint Android.bp resulting in a cc.Module
@@ -35,7 +33,7 @@
 	android.RegisterSingletonType("cmakelists_generator", cMakeListsGeneratorSingleton)
 }
 
-func cMakeListsGeneratorSingleton() blueprint.Singleton {
+func cMakeListsGeneratorSingleton() android.Singleton {
 	return &cmakelistsGeneratorSingleton{}
 }
 
@@ -57,14 +55,14 @@
 // This is done to ease investigating bug reports.
 var outputDebugInfo = false
 
-func (c *cmakelistsGeneratorSingleton) GenerateBuildActions(ctx blueprint.SingletonContext) {
+func (c *cmakelistsGeneratorSingleton) GenerateBuildActions(ctx android.SingletonContext) {
 	if getEnvVariable(envVariableGenerateCMakeLists, ctx) != envVariableTrue {
 		return
 	}
 
 	outputDebugInfo = (getEnvVariable(envVariableGenerateDebugInfo, ctx) == envVariableTrue)
 
-	ctx.VisitAllModules(func(module blueprint.Module) {
+	ctx.VisitAllModules(func(module android.Module) {
 		if ccModule, ok := module.(*Module); ok {
 			if compiledModule, ok := ccModule.compiler.(CompiledInterface); ok {
 				generateCLionProject(compiledModule, ctx, ccModule)
@@ -81,7 +79,7 @@
 	return
 }
 
-func getEnvVariable(name string, ctx blueprint.SingletonContext) string {
+func getEnvVariable(name string, ctx android.SingletonContext) string {
 	// Using android.Config.Getenv instead of os.getEnv to guarantee soong will
 	// re-run in case this environment variable changes.
 	return ctx.Config().(android.Config).Getenv(name)
@@ -116,7 +114,7 @@
 	return nil
 }
 
-func generateCLionProject(compiledModule CompiledInterface, ctx blueprint.SingletonContext, ccModule *Module) {
+func generateCLionProject(compiledModule CompiledInterface, ctx android.SingletonContext, ccModule *Module) {
 	srcs := compiledModule.Srcs()
 	if len(srcs) == 0 {
 		return
@@ -287,7 +285,7 @@
 	return flag
 }
 
-func parseCompilerParameters(params []string, ctx blueprint.SingletonContext, f *os.File) compilerParameters {
+func parseCompilerParameters(params []string, ctx android.SingletonContext, f *os.File) compilerParameters {
 	var compilerParameters = makeCompilerParameters()
 
 	for i, str := range params {
@@ -388,7 +386,7 @@
 	c1.flags = append(c1.flags, c2.flags...)
 }
 
-func evalVariable(ctx blueprint.SingletonContext, str string) (string, error) {
+func evalVariable(ctx android.SingletonContext, str string) (string, error) {
 	evaluated, err := ctx.Eval(pctx, str)
 	if err == nil {
 		return evaluated, nil
@@ -396,7 +394,7 @@
 	return "", err
 }
 
-func getCMakeListsForModule(module *Module, ctx blueprint.SingletonContext) string {
+func getCMakeListsForModule(module *Module, ctx android.SingletonContext) string {
 	return filepath.Join(getAndroidSrcRootDirectory(ctx),
 		cLionOutputProjectsDirectory,
 		path.Dir(ctx.BlueprintFile(module)),
@@ -406,7 +404,7 @@
 		cMakeListsFilename)
 }
 
-func getAndroidSrcRootDirectory(ctx blueprint.SingletonContext) string {
+func getAndroidSrcRootDirectory(ctx android.SingletonContext) string {
 	srcPath, _ := filepath.Abs(android.PathForSource(ctx).String())
 	return srcPath
 }
diff --git a/cc/config/global.go b/cc/config/global.go
index 4322436..8881b4b 100644
--- a/cc/config/global.go
+++ b/cc/config/global.go
@@ -216,14 +216,14 @@
 		[]string{"libnativehelper/include_deprecated"})
 
 	pctx.SourcePathVariable("ClangDefaultBase", ClangDefaultBase)
-	pctx.VariableFunc("ClangBase", func(config interface{}) (string, error) {
-		if override := config.(android.Config).Getenv("LLVM_PREBUILTS_BASE"); override != "" {
+	pctx.VariableFunc("ClangBase", func(config android.Config) (string, error) {
+		if override := config.Getenv("LLVM_PREBUILTS_BASE"); override != "" {
 			return override, nil
 		}
 		return "${ClangDefaultBase}", nil
 	})
-	pctx.VariableFunc("ClangVersion", func(config interface{}) (string, error) {
-		if override := config.(android.Config).Getenv("LLVM_PREBUILTS_VERSION"); override != "" {
+	pctx.VariableFunc("ClangVersion", func(config android.Config) (string, error) {
+		if override := config.Getenv("LLVM_PREBUILTS_VERSION"); override != "" {
 			return override, nil
 		}
 		return ClangDefaultVersion, nil
@@ -231,8 +231,8 @@
 	pctx.StaticVariable("ClangPath", "${ClangBase}/${HostPrebuiltTag}/${ClangVersion}")
 	pctx.StaticVariable("ClangBin", "${ClangPath}/bin")
 
-	pctx.VariableFunc("ClangShortVersion", func(config interface{}) (string, error) {
-		if override := config.(android.Config).Getenv("LLVM_RELEASE_VERSION"); override != "" {
+	pctx.VariableFunc("ClangShortVersion", func(config android.Config) (string, error) {
+		if override := config.Getenv("LLVM_RELEASE_VERSION"); override != "" {
 			return override, nil
 		}
 		return ClangDefaultShortVersion, nil
@@ -258,8 +258,8 @@
 			"frameworks/rs/script_api/include",
 		})
 
-	pctx.VariableFunc("CcWrapper", func(config interface{}) (string, error) {
-		if override := config.(android.Config).Getenv("CC_WRAPPER"); override != "" {
+	pctx.VariableFunc("CcWrapper", func(config android.Config) (string, error) {
+		if override := config.Getenv("CC_WRAPPER"); override != "" {
 			return override + " ", nil
 		}
 		return "", nil
diff --git a/cc/config/tidy.go b/cc/config/tidy.go
index a2fa5a2..76a5f9e 100644
--- a/cc/config/tidy.go
+++ b/cc/config/tidy.go
@@ -25,8 +25,8 @@
 	// Global tidy checks include only google*, performance*,
 	// and misc-macro-parentheses, but not google-readability*
 	// or google-runtime-references.
-	pctx.VariableFunc("TidyDefaultGlobalChecks", func(config interface{}) (string, error) {
-		if override := config.(android.Config).Getenv("DEFAULT_GLOBAL_TIDY_CHECKS"); override != "" {
+	pctx.VariableFunc("TidyDefaultGlobalChecks", func(config android.Config) (string, error) {
+		if override := config.Getenv("DEFAULT_GLOBAL_TIDY_CHECKS"); override != "" {
 			return override, nil
 		}
 		return strings.Join([]string{
@@ -41,8 +41,8 @@
 
 	// There are too many clang-tidy warnings in external and vendor projects.
 	// Enable only some google checks for these projects.
-	pctx.VariableFunc("TidyExternalVendorChecks", func(config interface{}) (string, error) {
-		if override := config.(android.Config).Getenv("DEFAULT_EXTERNAL_VENDOR_TIDY_CHECKS"); override != "" {
+	pctx.VariableFunc("TidyExternalVendorChecks", func(config android.Config) (string, error) {
+		if override := config.Getenv("DEFAULT_EXTERNAL_VENDOR_TIDY_CHECKS"); override != "" {
 			return override, nil
 		}
 		return strings.Join([]string{
diff --git a/cc/config/x86_darwin_host.go b/cc/config/x86_darwin_host.go
index 8d805c9..dbaa6fa 100644
--- a/cc/config/x86_darwin_host.go
+++ b/cc/config/x86_darwin_host.go
@@ -107,25 +107,25 @@
 )
 
 func init() {
-	pctx.VariableFunc("macSdkPath", func(config interface{}) (string, error) {
-		xcodeselect := config.(android.Config).HostSystemTool("xcode-select")
+	pctx.VariableFunc("macSdkPath", func(config android.Config) (string, error) {
+		xcodeselect := config.HostSystemTool("xcode-select")
 		bytes, err := exec.Command(xcodeselect, "--print-path").Output()
 		return strings.TrimSpace(string(bytes)), err
 	})
-	pctx.VariableFunc("macSdkRoot", func(config interface{}) (string, error) {
-		return xcrunSdk(config.(android.Config), "--show-sdk-path")
+	pctx.VariableFunc("macSdkRoot", func(config android.Config) (string, error) {
+		return xcrunSdk(config, "--show-sdk-path")
 	})
 	pctx.StaticVariable("macMinVersion", "10.8")
-	pctx.VariableFunc("MacArPath", func(config interface{}) (string, error) {
-		return xcrun(config.(android.Config), "--find", "ar")
+	pctx.VariableFunc("MacArPath", func(config android.Config) (string, error) {
+		return xcrun(config, "--find", "ar")
 	})
 
-	pctx.VariableFunc("MacStripPath", func(config interface{}) (string, error) {
-		return xcrun(config.(android.Config), "--find", "strip")
+	pctx.VariableFunc("MacStripPath", func(config android.Config) (string, error) {
+		return xcrun(config, "--find", "strip")
 	})
 
-	pctx.VariableFunc("MacToolPath", func(config interface{}) (string, error) {
-		path, err := xcrun(config.(android.Config), "--find", "ld")
+	pctx.VariableFunc("MacToolPath", func(config android.Config) (string, error) {
+		path, err := xcrun(config, "--find", "ld")
 		return filepath.Dir(path), err
 	})
 
diff --git a/cc/library.go b/cc/library.go
index 192496a..cf10617 100644
--- a/cc/library.go
+++ b/cc/library.go
@@ -85,9 +85,6 @@
 	VariantIsShared bool `blueprint:"mutated"`
 	// This variant is static
 	VariantIsStatic bool `blueprint:"mutated"`
-	// Location of the static library in the sysroot. Empty if the library is
-	// not included in the NDK.
-	NdkSysrootPath string `blueprint:"mutated"`
 }
 
 type FlagExporterProperties struct {
@@ -246,6 +243,10 @@
 	// Source Abi Diff
 	sAbiDiff android.OptionalPath
 
+	// Location of the static library in the sysroot. Empty if the library is
+	// not included in the NDK.
+	ndkSysrootPath android.Path
+
 	// Decorated interafaces
 	*baseCompiler
 	*baseLinker
@@ -742,7 +743,7 @@
 			Input:       file,
 		})
 
-		library.MutatedProperties.NdkSysrootPath = installPath.String()
+		library.ndkSysrootPath = installPath
 	}
 }
 
diff --git a/cc/ndk_headers.go b/cc/ndk_headers.go
index bfbf0f5..d7c2a06 100644
--- a/cc/ndk_headers.go
+++ b/cc/ndk_headers.go
@@ -74,7 +74,7 @@
 
 	properties headerProperies
 
-	installPaths []string
+	installPaths android.Paths
 	licensePath  android.ModuleSrcPath
 }
 
@@ -139,7 +139,7 @@
 				"expected header install path (%q) not equal to actual install path %q",
 				installPath, installedPath))
 		}
-		m.installPaths = append(m.installPaths, installPath.String())
+		m.installPaths = append(m.installPaths, installPath)
 	}
 
 	if len(m.installPaths) == 0 {
@@ -186,7 +186,7 @@
 
 	properties preprocessedHeaderProperies
 
-	installPaths []string
+	installPaths android.Paths
 	licensePath  android.ModuleSrcPath
 }
 
@@ -208,7 +208,7 @@
 		installDir := getHeaderInstallDir(ctx, header, String(m.properties.From), String(m.properties.To))
 		installPath := installDir.Join(ctx, header.Base())
 		installPaths = append(installPaths, installPath)
-		m.installPaths = append(m.installPaths, installPath.String())
+		m.installPaths = append(m.installPaths, installPath)
 	}
 
 	if len(m.installPaths) == 0 {
diff --git a/cc/ndk_library.go b/cc/ndk_library.go
index 96a90fb..e69128c 100644
--- a/cc/ndk_library.go
+++ b/cc/ndk_library.go
@@ -98,7 +98,7 @@
 	properties libraryProperties
 
 	versionScriptPath android.ModuleGenPath
-	installPath       string
+	installPath       android.Path
 }
 
 // OMG GO
@@ -344,7 +344,7 @@
 
 	installDir := getNdkInstallBase(ctx).Join(ctx, fmt.Sprintf(
 		"platforms/android-%s/arch-%s/usr/%s", apiLevel, arch, libDir))
-	stub.installPath = ctx.InstallFile(installDir, path.Base(), path).String()
+	stub.installPath = ctx.InstallFile(installDir, path.Base(), path)
 }
 
 func newStubLibrary() *Module {
diff --git a/cc/ndk_sysroot.go b/cc/ndk_sysroot.go
index e213965..4324458 100644
--- a/cc/ndk_sysroot.go
+++ b/cc/ndk_sysroot.go
@@ -53,8 +53,6 @@
 // TODO(danalbert): Write `ndk_static_library` rule.
 
 import (
-	"github.com/google/blueprint"
-
 	"android/soong/android"
 )
 
@@ -76,32 +74,32 @@
 	return getNdkInstallBase(ctx).Join(ctx, "sysroot")
 }
 
-func getNdkSysrootTimestampFile(ctx android.PathContext) android.Path {
+func getNdkSysrootTimestampFile(ctx android.PathContext) android.WritablePath {
 	return android.PathForOutput(ctx, "ndk.timestamp")
 }
 
-func NdkSingleton() blueprint.Singleton {
+func NdkSingleton() android.Singleton {
 	return &ndkSingleton{}
 }
 
 type ndkSingleton struct{}
 
-func (n *ndkSingleton) GenerateBuildActions(ctx blueprint.SingletonContext) {
-	installPaths := []string{}
-	licensePaths := []string{}
-	ctx.VisitAllModules(func(module blueprint.Module) {
+func (n *ndkSingleton) GenerateBuildActions(ctx android.SingletonContext) {
+	var installPaths android.Paths
+	var licensePaths android.Paths
+	ctx.VisitAllModules(func(module android.Module) {
 		if m, ok := module.(android.Module); ok && !m.Enabled() {
 			return
 		}
 
 		if m, ok := module.(*headerModule); ok {
 			installPaths = append(installPaths, m.installPaths...)
-			licensePaths = append(licensePaths, m.licensePath.String())
+			licensePaths = append(licensePaths, m.licensePath)
 		}
 
 		if m, ok := module.(*preprocessedHeaderModule); ok {
 			installPaths = append(installPaths, m.installPaths...)
-			licensePaths = append(licensePaths, m.licensePath.String())
+			licensePaths = append(licensePaths, m.licensePath)
 		}
 
 		if m, ok := module.(*Module); ok {
@@ -110,30 +108,28 @@
 			}
 
 			if library, ok := m.linker.(*libraryDecorator); ok {
-				if library.MutatedProperties.NdkSysrootPath != "" {
-					installPaths = append(installPaths, library.MutatedProperties.NdkSysrootPath)
+				if library.ndkSysrootPath != nil {
+					installPaths = append(installPaths, library.ndkSysrootPath)
 				}
 			}
 		}
 	})
 
 	combinedLicense := getNdkInstallBase(ctx).Join(ctx, "NOTICE")
-	ctx.Build(pctx, blueprint.BuildParams{
+	ctx.Build(pctx, android.BuildParams{
 		Rule:        android.Cat,
 		Description: "combine licenses",
-		Outputs:     []string{combinedLicense.String()},
+		Output:      combinedLicense,
 		Inputs:      licensePaths,
-		Optional:    true,
 	})
 
-	depPaths := append(installPaths, combinedLicense.String())
+	depPaths := append(installPaths, combinedLicense)
 
 	// There's a dummy "ndk" rule defined in ndk/Android.mk that depends on
 	// this. `m ndk` will build the sysroots.
-	ctx.Build(pctx, blueprint.BuildParams{
+	ctx.Build(pctx, android.BuildParams{
 		Rule:      android.Touch,
-		Outputs:   []string{getNdkSysrootTimestampFile(ctx).String()},
+		Output:    getNdkSysrootTimestampFile(ctx),
 		Implicits: depPaths,
-		Optional:  true,
 	})
 }