diff --git a/build/soong/compat_cil.go b/build/soong/compat_cil.go
new file mode 100644
index 0000000..230fdc3
--- /dev/null
+++ b/build/soong/compat_cil.go
@@ -0,0 +1,113 @@
+// Copyright 2021 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package selinux
+
+import (
+	"github.com/google/blueprint/proptools"
+
+	"android/soong/android"
+)
+
+func init() {
+	android.RegisterModuleType("se_compat_cil", compatCilFactory)
+}
+
+// se_compat_cil collects and installs backwards compatibility cil files.
+func compatCilFactory() android.Module {
+	c := &compatCil{}
+	c.AddProperties(&c.properties)
+	android.InitAndroidArchModule(c, android.DeviceSupported, android.MultilibCommon)
+	return c
+}
+
+type compatCil struct {
+	android.ModuleBase
+	properties    compatCilProperties
+	installSource android.Path
+	installPath   android.InstallPath
+}
+
+type compatCilProperties struct {
+	// List of source files. Can reference se_filegroup type modules with the ":module" syntax.
+	Srcs []string
+
+	// Output file name. Defaults to module name if unspecified.
+	Stem *string
+}
+
+func (c *compatCil) stem() string {
+	return proptools.StringDefault(c.properties.Stem, c.Name())
+}
+
+func (c *compatCil) expandSeSources(ctx android.ModuleContext) android.Paths {
+	srcPaths := make(android.Paths, 0, len(c.properties.Srcs))
+	for _, src := range c.properties.Srcs {
+		if m := android.SrcIsModule(src); m != "" {
+			module := ctx.GetDirectDepWithTag(m, android.SourceDepTag)
+			if module == nil {
+				// Error would have been handled by ExtractSourcesDeps
+				continue
+			}
+			if fg, ok := module.(*fileGroup); ok {
+				if c.SystemExtSpecific() {
+					srcPaths = append(srcPaths, fg.SystemExtPrivateSrcs()...)
+				} else {
+					srcPaths = append(srcPaths, fg.SystemPrivateSrcs()...)
+				}
+			} else {
+				ctx.PropertyErrorf("srcs", "%q is not an se_filegroup", m)
+			}
+		} else {
+			srcPaths = append(srcPaths, android.PathForModuleSrc(ctx, src))
+		}
+	}
+	return srcPaths
+}
+
+func (c *compatCil) DepsMutator(ctx android.BottomUpMutatorContext) {
+	android.ExtractSourcesDeps(ctx, c.properties.Srcs)
+}
+
+func (c *compatCil) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+	if c.ProductSpecific() || c.SocSpecific() || c.DeviceSpecific() {
+		ctx.ModuleErrorf("Compat cil files only support system and system_ext partitions")
+	}
+
+	srcPaths := c.expandSeSources(ctx)
+	out := android.PathForModuleGen(ctx, c.Name())
+	ctx.Build(pctx, android.BuildParams{
+		Rule:        android.Cat,
+		Inputs:      srcPaths,
+		Output:      out,
+		Description: "Combining compat cil for " + c.Name(),
+	})
+
+	c.installPath = android.PathForModuleInstall(ctx, "etc", "selinux", "mapping")
+	c.installSource = out
+	ctx.InstallFile(c.installPath, c.stem(), c.installSource)
+}
+
+func (c *compatCil) AndroidMkEntries() []android.AndroidMkEntries {
+	return []android.AndroidMkEntries{android.AndroidMkEntries{
+		Class:      "ETC",
+		OutputFile: android.OptionalPathForPath(c.installSource),
+		ExtraEntries: []android.AndroidMkExtraEntriesFunc{
+			func(ctx android.AndroidMkExtraEntriesContext, entries *android.AndroidMkEntries) {
+				entries.SetPath("LOCAL_MODULE_PATH", c.installPath.ToMakePath())
+				entries.SetString("LOCAL_INSTALLED_MODULE_STEM", c.stem())
+			},
+		},
+	}}
+}