diff --git a/file.go b/file.go
index 2aeca1d..f7d0e9b 100644
--- a/file.go
+++ b/file.go
@@ -3,6 +3,7 @@ package analysisutil
 import (
 	"go/ast"
 	"go/token"
+	"regexp"
 
 	"golang.org/x/tools/go/analysis"
 )
@@ -16,3 +17,14 @@ func File(pass *analysis.Pass, pos token.Pos) *ast.File {
 	}
 	return nil
 }
+
+var genCommentRegexp = regexp.MustCompile(`^// Code generated .* DO NOT EDIT\.$`)
+
+// IsGeneratedFile reports whether the file has been generated automatically.
+// If file is nil, IsGeneratedFile will return false.
+func IsGeneratedFile(file *ast.File) bool {
+	if file == nil || file.Doc == nil {
+		return false
+	}
+	return genCommentRegexp.MatchString(file.Doc.List[0].Text)
+}
diff --git a/file_test.go b/file_test.go
new file mode 100644
index 0000000..341e7c5
--- /dev/null
+++ b/file_test.go
@@ -0,0 +1,46 @@
+package analysisutil_test
+
+import (
+	"fmt"
+	"path/filepath"
+	"testing"
+
+	"github.com/gostaticanalysis/analysisutil"
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/analysistest"
+)
+
+func TestIsGeneratedFile(t *testing.T) {
+	t.Parallel()
+
+	cases := map[string]struct {
+		src  string
+		want bool
+	}{
+		"true":  {"// Code generated by test; DO NOT EDIT.", true},
+		"false": {"//Code generated by test; DO NOT EDIT.", false},
+		"empty": {"", false},
+	}
+
+	for name, tt := range cases {
+		name, tt := name, tt
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+			a := &analysis.Analyzer{
+				Name: name + "Analyzer",
+				Run: func(pass *analysis.Pass) (interface{}, error) {
+					got := analysisutil.IsGeneratedFile(pass.Files[0])
+					if tt.want != got {
+						return nil, fmt.Errorf("want %v but got %v", tt.want, got)
+					}
+					return nil, nil
+				},
+			}
+			path := filepath.Join(name, name+".go")
+			dir := WriteFiles(t, map[string]string{
+				path: fmt.Sprintf("%s\npackage %s", tt.src, name),
+			})
+			analysistest.Run(t, dir, a, name)
+		})
+	}
+}