diff --git a/cmd/release_config/build_flag/main.go b/cmd/release_config/build_flag/main.go
index a8e6326..67edc35 100644
--- a/cmd/release_config/build_flag/main.go
+++ b/cmd/release_config/build_flag/main.go
@@ -160,6 +160,9 @@
 	if err != nil {
 		return err
 	}
+	if release.AconfigFlagsOnly {
+		return fmt.Errorf("%s does not allow build flag overrides", targetRelease)
+	}
 	flagArtifact, ok := release.FlagArtifacts[name]
 	if !ok {
 		return fmt.Errorf("Unknown build flag %s", name)
diff --git a/cmd/release_config/crunch_flags/main.go b/cmd/release_config/crunch_flags/main.go
index b67374a..e107b9f 100644
--- a/cmd/release_config/crunch_flags/main.go
+++ b/cmd/release_config/crunch_flags/main.go
@@ -15,18 +15,29 @@
 	"google.golang.org/protobuf/proto"
 )
 
-// When a flag declaration has an initial value that is a string, the default workflow is PREBUILT.
-// If the flag name starts with any of prefixes in manualFlagNamePrefixes, it is MANUAL.
-var manualFlagNamePrefixes []string = []string{
-	"RELEASE_ACONFIG_",
-	"RELEASE_PLATFORM_",
-}
+var (
+	// When a flag declaration has an initial value that is a string, the default workflow is PREBUILT.
+	// If the flag name starts with any of prefixes in manualFlagNamePrefixes, it is MANUAL.
+	manualFlagNamePrefixes []string = []string{
+		"RELEASE_ACONFIG_",
+		"RELEASE_PLATFORM_",
+	}
 
-var defaultFlagNamespace string = "android_UNKNOWN"
+	// Set `aconfig_flags_only: true` in these release configs.
+	aconfigFlagsOnlyConfigs map[string]bool = map[string]bool{
+		"trunk_food": true,
+	}
+
+	// Default namespace value.  This is intentionally invalid.
+	defaultFlagNamespace string = "android_UNKNOWN"
+
+	// What is the current name for "next".
+	nextName string = "ap3a"
+)
 
 func RenameNext(name string) string {
 	if name == "next" {
-		return "ap3a"
+		return nextName
 	}
 	return name
 }
@@ -205,6 +216,9 @@
 				fmt.Printf("%s: Unexpected value %s=%s\n", path, valName, valValue)
 			}
 			if flagValue != nil {
+				if releaseProto.AconfigFlagsOnly {
+					return fmt.Errorf("%s does not allow build flag overrides", RenameNext(name))
+				}
 				valPath := filepath.Join(dir, "flag_values", RenameNext(name), fmt.Sprintf("%s.textproto", valName))
 				err := WriteFile(valPath, flagValue)
 				if err != nil {
@@ -285,6 +299,9 @@
 		releaseConfig := &rc_proto.ReleaseConfig{
 			Name: proto.String(RenameNext(name)),
 		}
+		if aconfigFlagsOnlyConfigs[name] {
+			releaseConfig.AconfigFlagsOnly = true
+		}
 		configFiles := config[configRegexp.SubexpIndex("files")]
 		files := strings.Split(strings.ReplaceAll(configFiles, "$(local_dir)", dir+"/"), " ")
 		configInherits := config[configRegexp.SubexpIndex("inherits")]
diff --git a/cmd/release_config/release_config_lib/release_config.go b/cmd/release_config/release_config_lib/release_config.go
index 5996c46..e51ff08 100644
--- a/cmd/release_config/release_config_lib/release_config.go
+++ b/cmd/release_config/release_config_lib/release_config.go
@@ -62,6 +62,10 @@
 	// The names of release configs that we inherit
 	InheritNames []string
 
+	// True if this release config only allows inheritance and aconfig flag
+	// overrides. Build flag value overrides are an error.
+	AconfigFlagsOnly bool
+
 	// Unmarshalled flag artifacts
 	FlagArtifacts FlagArtifacts
 
@@ -174,6 +178,9 @@
 			})
 
 		myDirsMap[contrib.DeclarationIndex] = true
+		if config.AconfigFlagsOnly && len(contrib.FlagValues) > 0 {
+			return fmt.Errorf("%s does not allow build flag overrides", config.Name)
+		}
 		for _, value := range contrib.FlagValues {
 			name := *value.proto.Name
 			fa, ok := config.FlagArtifacts[name]
diff --git a/cmd/release_config/release_config_lib/release_configs.go b/cmd/release_config/release_config_lib/release_configs.go
index 6b47091..e5fd99e 100644
--- a/cmd/release_config/release_config_lib/release_configs.go
+++ b/cmd/release_config/release_config_lib/release_configs.go
@@ -206,6 +206,9 @@
 		if err2 != nil {
 			return err2
 		}
+		if releaseConfigContribution.proto.GetAconfigFlagsOnly() {
+			config.AconfigFlagsOnly = true
+		}
 		m.ReleaseConfigContributions[name] = releaseConfigContribution
 		config.Contributions = append(config.Contributions, releaseConfigContribution)
 		return nil
diff --git a/cmd/release_config/release_config_proto/build_flags_src.pb.go b/cmd/release_config/release_config_proto/build_flags_src.pb.go
index 8054bd9..dded975 100644
--- a/cmd/release_config/release_config_proto/build_flags_src.pb.go
+++ b/cmd/release_config/release_config_proto/build_flags_src.pb.go
@@ -387,6 +387,8 @@
 	// List of names of the aconfig_value_set soong module(s) for this
 	// contribution.
 	AconfigValueSets []string `protobuf:"bytes,3,rep,name=aconfig_value_sets,json=aconfigValueSets" json:"aconfig_value_sets,omitempty"`
+	// Only aconfig flags are allowed in this release config.
+	AconfigFlagsOnly *bool `protobuf:"varint,4,opt,name=aconfig_flags_only,json=aconfigFlagsOnly" json:"aconfig_flags_only,omitempty"`
 }
 
 func (x *ReleaseConfig) Reset() {
@@ -442,6 +444,13 @@
 	return nil
 }
 
+func (x *ReleaseConfig) GetAconfigFlagsOnly() bool {
+	if x != nil && x.AconfigFlagsOnly != nil {
+		return *x.AconfigFlagsOnly
+	}
+	return false
+}
+
 // Any aliases.  These are used for continuous integration builder config.
 type ReleaseAlias struct {
 	state         protoimpl.MessageState
@@ -609,36 +618,39 @@
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+	0x5f, 0x63, 0x6f, 0x6e, 0x66, 0x69, 0x67, 0x5f, 0x70, 0x72, 0x6f, 0x74, 0x6f,
 }
 
 var (
diff --git a/cmd/release_config/release_config_proto/build_flags_src.proto b/cmd/release_config/release_config_proto/build_flags_src.proto
index 017e5d4..0ef1a5f 100644
--- a/cmd/release_config/release_config_proto/build_flags_src.proto
+++ b/cmd/release_config/release_config_proto/build_flags_src.proto
@@ -119,6 +119,9 @@
   // List of names of the aconfig_value_set soong module(s) for this
   // contribution.
   repeated string aconfig_value_sets = 3;
+
+  // Only aconfig flags are allowed in this release config.
+  optional bool aconfig_flags_only = 4;
 }
 
 // Any aliases.  These are used for continuous integration builder config.