diff --git a/android/filegroup.go b/android/filegroup.go
index 68311e3..ec522fc 100644
--- a/android/filegroup.go
+++ b/android/filegroup.go
@@ -15,7 +15,9 @@
 package android
 
 import (
+	"io"
 	"strings"
+	"text/template"
 )
 
 func init() {
@@ -69,8 +71,23 @@
 	return append(Paths{}, fg.srcs...)
 }
 
-func (fg *fileGroup) MakeVars(ctx MakeVarsModuleContext) {
-	if makeVar := String(fg.properties.Export_to_make_var); makeVar != "" {
-		ctx.StrictRaw(makeVar, strings.Join(fg.srcs.Strings(), " "))
+var androidMkTemplate = template.Must(template.New("filegroup").Parse(`
+ifdef {{.makeVar}}
+  $(error variable {{.makeVar}} set by soong module is already set in make)
+endif
+{{.makeVar}} := {{.value}}
+.KATI_READONLY := {{.makeVar}}
+`))
+
+func (fg *fileGroup) AndroidMk() AndroidMkData {
+	return AndroidMkData{
+		Custom: func(w io.Writer, name, prefix, moduleDir string, data AndroidMkData) {
+			if makeVar := String(fg.properties.Export_to_make_var); makeVar != "" {
+				androidMkTemplate.Execute(w, map[string]string{
+					"makeVar": makeVar,
+					"value":   strings.Join(fg.srcs.Strings(), " "),
+				})
+			}
+		},
 	}
 }
diff --git a/android/makevars.go b/android/makevars.go
index 86f4b42..ff7c8e4 100644
--- a/android/makevars.go
+++ b/android/makevars.go
@@ -17,7 +17,6 @@
 import (
 	"bytes"
 	"fmt"
-	"sort"
 	"strconv"
 	"strings"
 
@@ -35,16 +34,43 @@
 }
 
 ///////////////////////////////////////////////////////////////////////////////
-
-// BaseMakeVarsContext contains the common functions for other packages to use
-// to declare make variables
-type BaseMakeVarsContext interface {
+// Interface for other packages to use to declare make variables
+type MakeVarsContext interface {
 	Config() Config
 	DeviceConfig() DeviceConfig
 	AddNinjaFileDeps(deps ...string)
 
+	ModuleName(module blueprint.Module) string
+	ModuleDir(module blueprint.Module) string
+	ModuleSubDir(module blueprint.Module) string
+	ModuleType(module blueprint.Module) string
+	BlueprintFile(module blueprint.Module) string
+
+	ModuleErrorf(module blueprint.Module, format string, args ...interface{})
+	Errorf(format string, args ...interface{})
 	Failed() bool
 
+	VisitAllModules(visit func(Module))
+	VisitAllModulesIf(pred func(Module) bool, visit func(Module))
+
+	// Verify the make variable matches the Soong version, fail the build
+	// if it does not. If the make variable is empty, just set it.
+	Strict(name, ninjaStr string)
+	// Check to see if the make variable matches the Soong version, warn if
+	// it does not. If the make variable is empty, just set it.
+	Check(name, ninjaStr string)
+
+	// These are equivalent to the above, but sort the make and soong
+	// variables before comparing them. They also show the unique entries
+	// in each list when displaying the difference, instead of the entire
+	// string.
+	StrictSorted(name, ninjaStr string)
+	CheckSorted(name, ninjaStr string)
+
+	// Evaluates a ninja string and returns the result. Used if more
+	// complicated modification needs to happen before giving it to Make.
+	Eval(ninjaStr string) (string, error)
+
 	// These are equivalent to Strict and Check, but do not attempt to
 	// evaluate the values before writing them to the Makefile. They can
 	// be used when all ninja variables have already been evaluated through
@@ -82,48 +108,6 @@
 	DistForGoalsWithFilename(goals []string, path Path, filename string)
 }
 
-// MakeVarsContext contains the set of functions available for MakeVarsProvider
-// and SingletonMakeVarsProvider implementations.
-type MakeVarsContext interface {
-	BaseMakeVarsContext
-
-	ModuleName(module blueprint.Module) string
-	ModuleDir(module blueprint.Module) string
-	ModuleSubDir(module blueprint.Module) string
-	ModuleType(module blueprint.Module) string
-	BlueprintFile(module blueprint.Module) string
-
-	ModuleErrorf(module blueprint.Module, format string, args ...interface{})
-	Errorf(format string, args ...interface{})
-
-	VisitAllModules(visit func(Module))
-	VisitAllModulesIf(pred func(Module) bool, visit func(Module))
-
-	// Verify the make variable matches the Soong version, fail the build
-	// if it does not. If the make variable is empty, just set it.
-	Strict(name, ninjaStr string)
-	// Check to see if the make variable matches the Soong version, warn if
-	// it does not. If the make variable is empty, just set it.
-	Check(name, ninjaStr string)
-
-	// These are equivalent to the above, but sort the make and soong
-	// variables before comparing them. They also show the unique entries
-	// in each list when displaying the difference, instead of the entire
-	// string.
-	StrictSorted(name, ninjaStr string)
-	CheckSorted(name, ninjaStr string)
-
-	// Evaluates a ninja string and returns the result. Used if more
-	// complicated modification needs to happen before giving it to Make.
-	Eval(ninjaStr string) (string, error)
-}
-
-// MakeVarsModuleContext contains the set of functions available for modules
-// implementing the ModuleMakeVarsProvider interface.
-type MakeVarsModuleContext interface {
-	BaseMakeVarsContext
-}
-
 var _ PathContext = MakeVarsContext(nil)
 
 type MakeVarsProvider func(ctx MakeVarsContext)
@@ -151,14 +135,6 @@
 	return func(ctx MakeVarsContext) { singleton.MakeVars(ctx) }
 }
 
-// ModuleMakeVarsProvider is a Module with an extra method to provide extra values to be exported to Make.
-type ModuleMakeVarsProvider interface {
-	Module
-
-	// MakeVars uses a MakeVarsModuleContext to provide extra values to be exported to Make.
-	MakeVars(ctx MakeVarsModuleContext)
-}
-
 ///////////////////////////////////////////////////////////////////////////////
 
 func makeVarsSingletonFunc() Singleton {
@@ -233,45 +209,10 @@
 		dists = append(dists, mctx.dists...)
 	}
 
-	ctx.VisitAllModules(func(m Module) {
-		if provider, ok := m.(ModuleMakeVarsProvider); ok {
-			mctx := &makeVarsContext{
-				SingletonContext: ctx,
-			}
-
-			provider.MakeVars(mctx)
-
-			vars = append(vars, mctx.vars...)
-			phonies = append(phonies, mctx.phonies...)
-			dists = append(dists, mctx.dists...)
-		}
-	})
-
 	if ctx.Failed() {
 		return
 	}
 
-	sort.Slice(vars, func(i, j int) bool {
-		return vars[i].name < vars[j].name
-	})
-	sort.Slice(phonies, func(i, j int) bool {
-		return phonies[i].name < phonies[j].name
-	})
-	lessArr := func(a, b []string) bool {
-		if len(a) == len(b) {
-			for i := range a {
-				if a[i] < b[i] {
-					return true
-				}
-			}
-			return false
-		}
-		return len(a) < len(b)
-	}
-	sort.Slice(dists, func(i, j int) bool {
-		return lessArr(dists[i].goals, dists[j].goals) || lessArr(dists[i].paths, dists[j].paths)
-	})
-
 	outBytes := s.writeVars(vars)
 
 	if err := pathtools.WriteFileIfChanged(outFile, outBytes, 0666); err != nil {
diff --git a/android/prebuilt_build_tool.go b/android/prebuilt_build_tool.go
index 561771b..a9f29ef 100644
--- a/android/prebuilt_build_tool.go
+++ b/android/prebuilt_build_tool.go
@@ -29,10 +29,6 @@
 
 	// Extra files that should trigger rules using this tool to rebuild
 	Deps []string `android:"path,arch_variant"`
-
-	// Create a make variable with the specified name that contains the path to
-	// this prebuilt built tool, relative to the root of the source tree.
-	Export_to_make_var *string
 }
 
 type prebuiltBuildTool struct {
@@ -85,12 +81,6 @@
 	return t.toolPath
 }
 
-func (t *prebuiltBuildTool) MakeVars(ctx MakeVarsModuleContext) {
-	if makeVar := String(t.properties.Export_to_make_var); makeVar != "" {
-		ctx.StrictRaw(makeVar, t.toolPath.String())
-	}
-}
-
 var _ HostToolProvider = &prebuiltBuildTool{}
 
 // prebuilt_build_tool is to declare prebuilts to be used during the build, particularly for use
diff --git a/cc/gen.go b/cc/gen.go
index edae061..6f9036b 100644
--- a/cc/gen.go
+++ b/cc/gen.go
@@ -24,6 +24,8 @@
 )
 
 func init() {
+	pctx.SourcePathVariable("m4Cmd", "prebuilts/build-tools/${config.HostPrebuiltTag}/bin/m4")
+
 	pctx.HostBinToolVariable("aidlCmd", "aidl-cpp")
 	pctx.HostBinToolVariable("syspropCmd", "sysprop_cpp")
 }
diff --git a/cc/makevars.go b/cc/makevars.go
index dcfd6d8..968eeb5 100644
--- a/cc/makevars.go
+++ b/cc/makevars.go
@@ -148,6 +148,8 @@
 	ctx.Strict("AIDL_CPP", "${aidlCmd}")
 	ctx.Strict("ALLOWED_MANUAL_INTERFACE_PATHS", strings.Join(allowedManualInterfacePaths, " "))
 
+	ctx.Strict("M4", "${m4Cmd}")
+
 	ctx.Strict("RS_GLOBAL_INCLUDES", "${config.RsGlobalIncludes}")
 
 	ctx.Strict("SOONG_STRIP_PATH", "${stripPath}")