diff --git a/context.go b/context.go
index 96fd156..46c4e1a 100644
--- a/context.go
+++ b/context.go
@@ -142,6 +142,45 @@ type Context struct {
 
 	// String values that can be used to gate build graph traversal
 	includeTags *IncludeTags
+
+	sourceRootDirs *SourceRootDirs
+}
+
+// A container for String keys. The keys can be used to gate build graph traversal
+type SourceRootDirs struct {
+	dirs []string
+}
+
+func (dirs *SourceRootDirs) Add(names ...string) {
+	dirs.dirs = append(dirs.dirs, names...)
+}
+
+func (dirs *SourceRootDirs) SourceRootDirAllowed(path string) (bool, string) {
+	sort.Slice(dirs.dirs, func(i, j int) bool {
+		return len(dirs.dirs[i]) < len(dirs.dirs[j])
+	})
+	last := len(dirs.dirs)
+	for i := range dirs.dirs {
+		// iterate from longest paths (most specific)
+		prefix := dirs.dirs[last-i-1]
+		disallowedPrefix := false
+		if len(prefix) >= 1 && prefix[0] == '-' {
+			prefix = prefix[1:]
+			disallowedPrefix = true
+		}
+		if strings.HasPrefix(path, prefix) {
+			if disallowedPrefix {
+				return false, prefix
+			} else {
+				return true, prefix
+			}
+		}
+	}
+	return true, ""
+}
+
+func (c *Context) AddSourceRootDirs(dirs ...string) {
+	c.sourceRootDirs.Add(dirs...)
 }
 
 // A container for String keys. The keys can be used to gate build graph traversal
@@ -427,6 +466,7 @@ func newContext() *Context {
 		fs:                 pathtools.OsFs,
 		finishedMutators:   make(map[*mutatorInfo]bool),
 		includeTags:        &IncludeTags{},
+		sourceRootDirs:     &SourceRootDirs{},
 		outDir:             nil,
 		requiredNinjaMajor: 1,
 		requiredNinjaMinor: 7,
@@ -968,15 +1008,25 @@ func (c *Context) ParseBlueprintsFiles(rootFile string,
 	return c.ParseFileList(baseDir, pathsToParse, config)
 }
 
+type shouldVisitFileInfo struct {
+	shouldVisitFile bool
+	skippedModules  []string
+	reasonForSkip   string
+	errs            []error
+}
+
 // Returns a boolean for whether this file should be analyzed
 // Evaluates to true if the file either
 // 1. does not contain a blueprint_package_includes
 // 2. contains a blueprint_package_includes and all requested tags are set
 // This should be processed before adding any modules to the build graph
-func shouldVisitFile(c *Context, file *parser.File) (bool, []error) {
+func shouldVisitFile(c *Context, file *parser.File) shouldVisitFileInfo {
+	skippedModules := []string{}
+	var blueprintPackageIncludes *PackageIncludes
 	for _, def := range file.Defs {
 		switch def := def.(type) {
 		case *parser.Module:
+			skippedModules = append(skippedModules, def.Name())
 			if def.Type != "blueprint_package_includes" {
 				continue
 			}
@@ -984,14 +1034,43 @@ func shouldVisitFile(c *Context, file *parser.File) (bool, []error) {
 			if len(errs) > 0 {
 				// This file contains errors in blueprint_package_includes
 				// Visit anyways so that we can report errors on other modules in the file
-				return true, errs
+				return shouldVisitFileInfo{
+					shouldVisitFile: true,
+					errs:            errs,
+				}
 			}
 			logicModule, _ := c.cloneLogicModule(module)
-			pi := logicModule.(*PackageIncludes)
-			return pi.MatchesIncludeTags(c), []error{}
+			blueprintPackageIncludes = logicModule.(*PackageIncludes)
 		}
 	}
-	return true, []error{}
+
+	if blueprintPackageIncludes != nil {
+		packageMatches := blueprintPackageIncludes.MatchesIncludeTags(c)
+		if !packageMatches {
+			return shouldVisitFileInfo{
+				shouldVisitFile: false,
+				skippedModules:  skippedModules,
+				reasonForSkip: fmt.Sprintf(
+					"module is defined in %q which contains a blueprint_package_includes module with unsatisfied tags",
+					file.Name,
+				),
+			}
+		}
+	}
+
+	shouldVisit, invalidatingPrefix := c.sourceRootDirs.SourceRootDirAllowed(file.Name)
+	if !shouldVisit {
+		return shouldVisitFileInfo{
+			shouldVisitFile: shouldVisit,
+			skippedModules:  skippedModules,
+			reasonForSkip: fmt.Sprintf(
+				"%q is a descendant of %q, and that path prefix was not included in PRODUCT_SOURCE_ROOT_DIRS",
+				file.Name,
+				invalidatingPrefix,
+			),
+		}
+	}
+	return shouldVisitFileInfo{shouldVisitFile: true}
 }
 
 func (c *Context) ParseFileList(rootDir string, filePaths []string,
@@ -1009,9 +1088,15 @@ func (c *Context) ParseFileList(rootDir string, filePaths []string,
 		added chan<- struct{}
 	}
 
+	type newSkipInfo struct {
+		shouldVisitFileInfo
+		file string
+	}
+
 	moduleCh := make(chan newModuleInfo)
 	errsCh := make(chan []error)
 	doneCh := make(chan struct{})
+	skipCh := make(chan newSkipInfo)
 	var numErrs uint32
 	var numGoroutines int32
 
@@ -1046,12 +1131,17 @@ func (c *Context) ParseFileList(rootDir string, filePaths []string,
 			}
 			return nil
 		}
-		shouldVisit, errs := shouldVisitFile(c, file)
+		shouldVisitInfo := shouldVisitFile(c, file)
+		errs := shouldVisitInfo.errs
 		if len(errs) > 0 {
 			atomic.AddUint32(&numErrs, uint32(len(errs)))
 			errsCh <- errs
 		}
-		if !shouldVisit {
+		if !shouldVisitInfo.shouldVisitFile {
+			skipCh <- newSkipInfo{
+				file:                file.Name,
+				shouldVisitFileInfo: shouldVisitInfo,
+			}
 			// TODO: Write a file that lists the skipped bp files
 			return
 		}
@@ -1108,6 +1198,14 @@ loop:
 			if n == 0 {
 				break loop
 			}
+		case skipped := <-skipCh:
+			nctx := newNamespaceContextFromFilename(skipped.file)
+			for _, name := range skipped.skippedModules {
+				c.nameInterface.NewSkippedModule(nctx, name, SkippedModuleInfo{
+					filename: skipped.file,
+					reason:   skipped.reasonForSkip,
+				})
+			}
 		}
 	}
 
@@ -3515,7 +3613,6 @@ func (c *Context) discoveredMissingDependencies(module *moduleInfo, depName stri
 
 func (c *Context) missingDependencyError(module *moduleInfo, depName string) (errs error) {
 	err := c.nameInterface.MissingDependencyError(module.Name(), module.namespace(), depName)
-
 	return &BlueprintError{
 		Err: err,
 		Pos: module.pos,
diff --git a/context_test.go b/context_test.go
index 2c0a6c0..2ea7801 100644
--- a/context_test.go
+++ b/context_test.go
@@ -1272,3 +1272,293 @@ func TestDeduplicateOrderOnlyDeps(t *testing.T) {
 		})
 	}
 }
+
+func TestSourceRootDirAllowed(t *testing.T) {
+	type pathCase struct {
+		path           string
+		decidingPrefix string
+		allowed        bool
+	}
+	testcases := []struct {
+		desc      string
+		rootDirs  []string
+		pathCases []pathCase
+	}{
+		{
+			desc: "simple case",
+			rootDirs: []string{
+				"a",
+				"b/c/d",
+				"-c",
+				"-d/c/a",
+				"c/some_single_file",
+			},
+			pathCases: []pathCase{
+				{
+					path:           "a",
+					decidingPrefix: "a",
+					allowed:        true,
+				},
+				{
+					path:           "a/b/c",
+					decidingPrefix: "a",
+					allowed:        true,
+				},
+				{
+					path:           "b",
+					decidingPrefix: "",
+					allowed:        true,
+				},
+				{
+					path:           "b/c/d/a",
+					decidingPrefix: "b/c/d",
+					allowed:        true,
+				},
+				{
+					path:           "c",
+					decidingPrefix: "c",
+					allowed:        false,
+				},
+				{
+					path:           "c/a/b",
+					decidingPrefix: "c",
+					allowed:        false,
+				},
+				{
+					path:           "c/some_single_file",
+					decidingPrefix: "c/some_single_file",
+					allowed:        true,
+				},
+				{
+					path:           "d/c/a/abc",
+					decidingPrefix: "d/c/a",
+					allowed:        false,
+				},
+			},
+		},
+		{
+			desc: "root directory order matters",
+			rootDirs: []string{
+				"-a",
+				"a/c/some_allowed_file",
+				"a/b/d/some_allowed_file",
+				"a/b",
+				"a/c",
+				"-a/b/d",
+			},
+			pathCases: []pathCase{
+				{
+					path:           "a",
+					decidingPrefix: "a",
+					allowed:        false,
+				},
+				{
+					path:           "a/some_disallowed_file",
+					decidingPrefix: "a",
+					allowed:        false,
+				},
+				{
+					path:           "a/c/some_allowed_file",
+					decidingPrefix: "a/c/some_allowed_file",
+					allowed:        true,
+				},
+				{
+					path:           "a/b/d/some_allowed_file",
+					decidingPrefix: "a/b/d/some_allowed_file",
+					allowed:        true,
+				},
+				{
+					path:           "a/b/c",
+					decidingPrefix: "a/b",
+					allowed:        true,
+				},
+				{
+					path:           "a/b/c/some_allowed_file",
+					decidingPrefix: "a/b",
+					allowed:        true,
+				},
+				{
+					path:           "a/b/d",
+					decidingPrefix: "a/b/d",
+					allowed:        false,
+				},
+			},
+		},
+	}
+	for _, tc := range testcases {
+		dirs := SourceRootDirs{}
+		dirs.Add(tc.rootDirs...)
+		for _, pc := range tc.pathCases {
+			t.Run(fmt.Sprintf("%s: %s", tc.desc, pc.path), func(t *testing.T) {
+				allowed, decidingPrefix := dirs.SourceRootDirAllowed(pc.path)
+				if allowed != pc.allowed {
+					if pc.allowed {
+						t.Errorf("expected path %q to be allowed, but was not; root allowlist: %q", pc.path, tc.rootDirs)
+					} else {
+						t.Errorf("path %q was allowed unexpectedly; root allowlist: %q", pc.path, tc.rootDirs)
+					}
+				}
+				if decidingPrefix != pc.decidingPrefix {
+					t.Errorf("expected decidingPrefix to be %q, but got %q", pc.decidingPrefix, decidingPrefix)
+				}
+			})
+		}
+	}
+}
+
+func TestSourceRootDirs(t *testing.T) {
+	root_foo_bp := `
+	foo_module {
+		name: "foo",
+		deps: ["foo_dir1", "foo_dir_ignored_special_case"],
+	}
+	`
+	dir1_foo_bp := `
+	foo_module {
+		name: "foo_dir1",
+		deps: ["foo_dir_ignored"],
+	}
+	`
+	dir_ignored_foo_bp := `
+	foo_module {
+		name: "foo_dir_ignored",
+	}
+	`
+	dir_ignored_special_case_foo_bp := `
+	foo_module {
+		name: "foo_dir_ignored_special_case",
+	}
+	`
+	mockFs := map[string][]byte{
+		"Android.bp":                          []byte(root_foo_bp),
+		"dir1/Android.bp":                     []byte(dir1_foo_bp),
+		"dir_ignored/Android.bp":              []byte(dir_ignored_foo_bp),
+		"dir_ignored/special_case/Android.bp": []byte(dir_ignored_special_case_foo_bp),
+	}
+	fileList := []string{}
+	for f := range mockFs {
+		fileList = append(fileList, f)
+	}
+	testCases := []struct {
+		sourceRootDirs       []string
+		expectedModuleDefs   []string
+		unexpectedModuleDefs []string
+		expectedErrs         []string
+	}{
+		{
+			sourceRootDirs: []string{},
+			expectedModuleDefs: []string{
+				"foo",
+				"foo_dir1",
+				"foo_dir_ignored",
+				"foo_dir_ignored_special_case",
+			},
+		},
+		{
+			sourceRootDirs: []string{"-", ""},
+			unexpectedModuleDefs: []string{
+				"foo",
+				"foo_dir1",
+				"foo_dir_ignored",
+				"foo_dir_ignored_special_case",
+			},
+		},
+		{
+			sourceRootDirs: []string{"-"},
+			unexpectedModuleDefs: []string{
+				"foo",
+				"foo_dir1",
+				"foo_dir_ignored",
+				"foo_dir_ignored_special_case",
+			},
+		},
+		{
+			sourceRootDirs: []string{"dir1"},
+			expectedModuleDefs: []string{
+				"foo",
+				"foo_dir1",
+				"foo_dir_ignored",
+				"foo_dir_ignored_special_case",
+			},
+		},
+		{
+			sourceRootDirs: []string{"-dir1"},
+			expectedModuleDefs: []string{
+				"foo",
+				"foo_dir_ignored",
+				"foo_dir_ignored_special_case",
+			},
+			unexpectedModuleDefs: []string{
+				"foo_dir1",
+			},
+			expectedErrs: []string{
+				"Android.bp:2:2: \"foo\" depends on undefined module \"foo_dir1\"",
+			},
+		},
+		{
+			sourceRootDirs: []string{"-", "dir1"},
+			expectedModuleDefs: []string{
+				"foo_dir1",
+			},
+			unexpectedModuleDefs: []string{
+				"foo",
+				"foo_dir_ignored",
+				"foo_dir_ignored_special_case",
+			},
+			expectedErrs: []string{
+				"dir1/Android.bp:2:2: \"foo_dir1\" depends on undefined module \"foo_dir_ignored\"",
+			},
+		},
+		{
+			sourceRootDirs: []string{"-", "dir1", "dir_ignored/special_case/Android.bp"},
+			expectedModuleDefs: []string{
+				"foo_dir1",
+				"foo_dir_ignored_special_case",
+			},
+			unexpectedModuleDefs: []string{
+				"foo",
+				"foo_dir_ignored",
+			},
+			expectedErrs: []string{
+				"dir1/Android.bp:2:2: \"foo_dir1\" depends on undefined module \"foo_dir_ignored\"",
+			},
+		},
+	}
+	for _, tc := range testCases {
+		t.Run(fmt.Sprintf(`source root dirs are %q`, tc.sourceRootDirs), func(t *testing.T) {
+			ctx := NewContext()
+			ctx.MockFileSystem(mockFs)
+			ctx.RegisterModuleType("foo_module", newFooModule)
+			ctx.RegisterBottomUpMutator("deps", depsMutator)
+			ctx.AddSourceRootDirs(tc.sourceRootDirs...)
+			RegisterPackageIncludesModuleType(ctx)
+			ctx.ParseFileList(".", fileList, nil)
+			_, actualErrs := ctx.ResolveDependencies(nil)
+
+			stringErrs := []string(nil)
+			for i := range actualErrs {
+				stringErrs = append(stringErrs, fmt.Sprint(actualErrs[i]))
+			}
+			if !reflect.DeepEqual(tc.expectedErrs, stringErrs) {
+				t.Errorf("expected to find errors %v; got %v", tc.expectedErrs, stringErrs)
+			}
+			for _, modName := range tc.expectedModuleDefs {
+				allMods := ctx.moduleGroupFromName(modName, nil)
+				if allMods == nil || len(allMods.modules) != 1 {
+					mods := modulesOrAliases{}
+					if allMods != nil {
+						mods = allMods.modules
+					}
+					t.Errorf("expected to find one definition for module %q, but got %v", modName, mods)
+				}
+			}
+
+			for _, modName := range tc.unexpectedModuleDefs {
+				allMods := ctx.moduleGroupFromName(modName, nil)
+				if allMods != nil {
+					t.Errorf("expected to find no definitions for module %q, but got %v", modName, allMods.modules)
+				}
+			}
+		})
+	}
+}
diff --git a/name_interface.go b/name_interface.go
index 5e7e16e..c675ded 100644
--- a/name_interface.go
+++ b/name_interface.go
@@ -16,7 +16,9 @@ package blueprint
 
 import (
 	"fmt"
+	"os"
 	"sort"
+	"strings"
 )
 
 // This file exposes the logic of locating a module via a query string, to enable
@@ -54,6 +56,9 @@ type NameInterface interface {
 	// Gets called when a new module is created
 	NewModule(ctx NamespaceContext, group ModuleGroup, module Module) (namespace Namespace, err []error)
 
+	// Gets called when a module was pruned from the build tree by SourceRootDirs
+	NewSkippedModule(ctx NamespaceContext, name string, skipInfo SkippedModuleInfo)
+
 	// Finds the module with the given name
 	ModuleFromName(moduleName string, namespace Namespace) (group ModuleGroup, found bool)
 
@@ -88,18 +93,29 @@ func newNamespaceContext(moduleInfo *moduleInfo) (ctx NamespaceContext) {
 	return &namespaceContextImpl{moduleInfo.pos.Filename}
 }
 
+func newNamespaceContextFromFilename(filename string) NamespaceContext {
+	return &namespaceContextImpl{filename}
+}
+
 func (ctx *namespaceContextImpl) ModulePath() string {
 	return ctx.modulePath
 }
 
+type SkippedModuleInfo struct {
+	filename string
+	reason   string
+}
+
 // a SimpleNameInterface just stores all modules in a map based on name
 type SimpleNameInterface struct {
-	modules map[string]ModuleGroup
+	modules        map[string]ModuleGroup
+	skippedModules map[string][]SkippedModuleInfo
 }
 
 func NewSimpleNameInterface() *SimpleNameInterface {
 	return &SimpleNameInterface{
-		modules: make(map[string]ModuleGroup),
+		modules:        make(map[string]ModuleGroup),
+		skippedModules: make(map[string][]SkippedModuleInfo),
 	}
 }
 
@@ -118,8 +134,31 @@ func (s *SimpleNameInterface) NewModule(ctx NamespaceContext, group ModuleGroup,
 	return nil, []error{}
 }
 
+func (s *SimpleNameInterface) NewSkippedModule(ctx NamespaceContext, name string, info SkippedModuleInfo) {
+	if name == "" {
+		return
+	}
+	s.skippedModules[name] = append(s.skippedModules[name], info)
+}
+
 func (s *SimpleNameInterface) ModuleFromName(moduleName string, namespace Namespace) (group ModuleGroup, found bool) {
 	group, found = s.modules[moduleName]
+	skipInfos, skipped := s.skippedModules[moduleName]
+	if skipped {
+		filesFound := make([]string, 0, len(skipInfos))
+		reasons := make([]string, 0, len(skipInfos))
+		for _, info := range skipInfos {
+			filesFound = append(filesFound, info.filename)
+			reasons = append(reasons, info.reason)
+		}
+		fmt.Fprintf(
+			os.Stderr,
+			"module %q was defined in files(s) [%v], but was skipped for reason(s) [%v]\n",
+			moduleName,
+			strings.Join(filesFound, ", "),
+			strings.Join(reasons, "; "),
+		)
+	}
 	return group, found
 }
 
diff --git a/parser/ast.go b/parser/ast.go
index fee2ec2..ea774e6 100644
--- a/parser/ast.go
+++ b/parser/ast.go
@@ -60,6 +60,8 @@ type Module struct {
 	Type    string
 	TypePos scanner.Position
 	Map
+	//TODO(delmerico) make this a private field once ag/21588220 lands
+	Name__internal_only *string
 }
 
 func (m *Module) Copy() *Module {
@@ -86,6 +88,28 @@ func (m *Module) definitionTag() {}
 func (m *Module) Pos() scanner.Position { return m.TypePos }
 func (m *Module) End() scanner.Position { return m.Map.End() }
 
+func (m *Module) Name() string {
+	if m.Name__internal_only != nil {
+		return *m.Name__internal_only
+	}
+	for _, prop := range m.Properties {
+		if prop.Name == "name" {
+			if stringProp, ok := prop.Value.(*String); ok {
+				name := stringProp.Value
+				m.Name__internal_only = &name
+			} else {
+				name := prop.Value.String()
+				m.Name__internal_only = &name
+			}
+		}
+	}
+	if m.Name__internal_only == nil {
+		name := ""
+		m.Name__internal_only = &name
+	}
+	return *m.Name__internal_only
+}
+
 // A Property is a name: value pair within a Map, which may be a top level Module.
 type Property struct {
 	Name     string