diff --git a/bootstrap/bootstrap.go b/bootstrap/bootstrap.go
index 1dce684..e0a6e06 100644
--- a/bootstrap/bootstrap.go
+++ b/bootstrap/bootstrap.go
@@ -149,7 +149,7 @@ var (
 		},
 		"depfile")
 
-	_ = pctx.VariableFunc("ToolDir", func(config interface{}) (string, error) {
+	_ = pctx.VariableFunc("ToolDir", func(ctx blueprint.VariableFuncContext, config interface{}) (string, error) {
 		return config.(BootstrapConfig).HostToolDir(), nil
 	})
 )
diff --git a/bootstrap/config.go b/bootstrap/config.go
index 802aa05..1d256ba 100644
--- a/bootstrap/config.go
+++ b/bootstrap/config.go
@@ -25,7 +25,7 @@ import (
 )
 
 func bootstrapVariable(name string, value func(BootstrapConfig) string) blueprint.Variable {
-	return pctx.VariableFunc(name, func(config interface{}) (string, error) {
+	return pctx.VariableFunc(name, func(ctx blueprint.VariableFuncContext, config interface{}) (string, error) {
 		c, ok := config.(BootstrapConfig)
 		if !ok {
 			panic(fmt.Sprintf("Bootstrap rules were passed a configuration that does not include theirs, config=%q",
diff --git a/bootstrap/glob.go b/bootstrap/glob.go
index 70495dc..77de891 100644
--- a/bootstrap/glob.go
+++ b/bootstrap/glob.go
@@ -44,7 +44,7 @@ import (
 // in a build failure with a "missing and no known rule to make it" error.
 
 var (
-	_ = pctx.VariableFunc("globCmd", func(config interface{}) (string, error) {
+	_ = pctx.VariableFunc("globCmd", func(ctx blueprint.VariableFuncContext, config interface{}) (string, error) {
 		return filepath.Join(config.(BootstrapConfig).SoongOutDir(), "bpglob"), nil
 	})
 
diff --git a/context.go b/context.go
index 5448f1e..fa6c1fe 100644
--- a/context.go
+++ b/context.go
@@ -1798,7 +1798,7 @@ func (c *Context) resolveDependencies(ctx context.Context, config interface{}) (
 	pprof.Do(ctx, pprof.Labels("blueprint", "ResolveDependencies"), func(ctx context.Context) {
 		c.initProviders()
 
-		c.liveGlobals = newLiveTracker(config)
+		c.liveGlobals = newLiveTracker(c, config)
 
 		deps, errs = c.generateSingletonBuildActions(config, c.preSingletonInfo, c.liveGlobals)
 		if len(errs) > 0 {
@@ -4413,7 +4413,7 @@ func (c *Context) writeLocalBuildActions(nw *ninjaWriter,
 		// A localVariable doesn't need the package names or config to
 		// determine its name or value.
 		name := v.fullName(nil)
-		value, err := v.value(nil)
+		value, err := v.value(nil, nil)
 		if err != nil {
 			panic(err)
 		}
diff --git a/live_tracker.go b/live_tracker.go
index 1d48e58..ef9c8a9 100644
--- a/live_tracker.go
+++ b/live_tracker.go
@@ -23,14 +23,16 @@ import "sync"
 type liveTracker struct {
 	sync.Mutex
 	config interface{} // Used to evaluate variable, rule, and pool values.
+	ctx    *Context    // Used to evaluate globs
 
 	variables map[Variable]ninjaString
 	pools     map[Pool]*poolDef
 	rules     map[Rule]*ruleDef
 }
 
-func newLiveTracker(config interface{}) *liveTracker {
+func newLiveTracker(ctx *Context, config interface{}) *liveTracker {
 	return &liveTracker{
+		ctx:       ctx,
 		config:    config,
 		variables: make(map[Variable]ninjaString),
 		pools:     make(map[Pool]*poolDef),
@@ -153,7 +155,9 @@ func (l *liveTracker) addPool(p Pool) error {
 func (l *liveTracker) addVariable(v Variable) error {
 	_, ok := l.variables[v]
 	if !ok {
-		value, err := v.value(l.config)
+		ctx := &variableFuncContext{l.ctx}
+
+		value, err := v.value(ctx, l.config)
 		if err == errVariableIsArg {
 			// This variable is a placeholder for an argument that can be passed
 			// to a rule.  It has no value and thus doesn't reference any other
diff --git a/package_ctx.go b/package_ctx.go
index 1eafdb9..07b7a9c 100644
--- a/package_ctx.go
+++ b/package_ctx.go
@@ -59,7 +59,7 @@ type PackageContext interface {
 	ImportAs(as, pkgPath string)
 
 	StaticVariable(name, value string) Variable
-	VariableFunc(name string, f func(config interface{}) (string, error)) Variable
+	VariableFunc(name string, f func(ctx VariableFuncContext, config interface{}) (string, error)) Variable
 	VariableConfigMethod(name string, method interface{}) Variable
 
 	StaticPool(name string, params PoolParams) Pool
@@ -304,7 +304,7 @@ func (v *staticVariable) memoizeFullName(pkgNames map[*packageContext]string) {
 	v.fullName_ = v.fullName(pkgNames)
 }
 
-func (v *staticVariable) value(interface{}) (ninjaString, error) {
+func (v *staticVariable) value(VariableFuncContext, interface{}) (ninjaString, error) {
 	ninjaStr, err := parseNinjaString(v.pctx.scope, v.value_)
 	if err != nil {
 		err = fmt.Errorf("error parsing variable %s value: %s", v, err)
@@ -320,10 +320,30 @@ func (v *staticVariable) String() string {
 type variableFunc struct {
 	pctx      *packageContext
 	name_     string
-	value_    func(interface{}) (string, error)
+	value_    func(VariableFuncContext, interface{}) (string, error)
 	fullName_ string
 }
 
+// VariableFuncContext is passed to VariableFunc functions.
+type VariableFuncContext interface {
+	// GlobWithDeps returns a list of files and directories that match the
+	// specified pattern but do not match any of the patterns in excludes.
+	// Any directories will have a '/' suffix.  It also adds efficient
+	// dependencies to rerun the primary builder whenever a file matching
+	// the pattern as added or removed, without rerunning if a file that
+	// does not match the pattern is added to a searched directory.
+	GlobWithDeps(globPattern string, excludes []string) ([]string, error)
+}
+
+type variableFuncContext struct {
+	context *Context
+}
+
+func (v *variableFuncContext) GlobWithDeps(pattern string,
+	excludes []string) ([]string, error) {
+	return v.context.glob(pattern, excludes)
+}
+
 // VariableFunc returns a Variable whose value is determined by a function that
 // takes a config object as input and returns either the variable value or an
 // error.  It may only be called during a Go package's initialization - either
@@ -336,7 +356,7 @@ type variableFunc struct {
 // reference other Ninja variables that are visible within the calling Go
 // package.
 func (p *packageContext) VariableFunc(name string,
-	f func(config interface{}) (string, error)) Variable {
+	f func(ctx VariableFuncContext, config interface{}) (string, error)) Variable {
 
 	checkCalledFromInit()
 
@@ -382,7 +402,7 @@ func (p *packageContext) VariableConfigMethod(name string,
 	methodValue := reflect.ValueOf(method)
 	validateVariableMethod(name, methodValue)
 
-	fun := func(config interface{}) (string, error) {
+	fun := func(ctx VariableFuncContext, config interface{}) (string, error) {
 		result := methodValue.Call([]reflect.Value{reflect.ValueOf(config)})
 		resultStr := result[0].Interface().(string)
 		return resultStr, nil
@@ -420,8 +440,8 @@ func (v *variableFunc) memoizeFullName(pkgNames map[*packageContext]string) {
 	v.fullName_ = v.fullName(pkgNames)
 }
 
-func (v *variableFunc) value(config interface{}) (ninjaString, error) {
-	value, err := v.value_(config)
+func (v *variableFunc) value(ctx VariableFuncContext, config interface{}) (ninjaString, error) {
+	value, err := v.value_(ctx, config)
 	if err != nil {
 		return nil, err
 	}
@@ -484,7 +504,7 @@ func (v *argVariable) memoizeFullName(pkgNames map[*packageContext]string) {
 	// Nothing to do, full name is known at initialization.
 }
 
-func (v *argVariable) value(config interface{}) (ninjaString, error) {
+func (v *argVariable) value(ctx VariableFuncContext, config interface{}) (ninjaString, error) {
 	return nil, errVariableIsArg
 }
 
diff --git a/scope.go b/scope.go
index 3f39eb7..9585559 100644
--- a/scope.go
+++ b/scope.go
@@ -29,7 +29,7 @@ type Variable interface {
 	name() string                                        // "foo"
 	fullName(pkgNames map[*packageContext]string) string // "pkg.foo" or "path.to.pkg.foo"
 	memoizeFullName(pkgNames map[*packageContext]string) // precompute fullName if desired
-	value(config interface{}) (ninjaString, error)
+	value(ctx VariableFuncContext, config interface{}) (ninjaString, error)
 	String() string
 }
 
@@ -373,7 +373,7 @@ func (l *localVariable) memoizeFullName(pkgNames map[*packageContext]string) {
 	// Nothing to do, full name is known at initialization.
 }
 
-func (l *localVariable) value(interface{}) (ninjaString, error) {
+func (l *localVariable) value(VariableFuncContext, interface{}) (ninjaString, error) {
 	return l.value_, nil
 }