diff --git a/src/go/build/build.go b/src/go/build/build.go
index 5a14d1ac33..5d87d9fb9e 100644
--- a/src/go/build/build.go
+++ b/src/go/build/build.go
@@ -410,11 +410,16 @@ func (ctxt *Context) ImportDir(dir string, mode ImportMode) (*Package, error) {
 // containing no buildable Go source files. (It may still contain
 // test files, files hidden by build tags, and so on.)
 type NoGoError struct {
-	Dir string
+	Dir     string
+	Ignored bool // whether any Go files were ignored due to build tags
 }
 
 func (e *NoGoError) Error() string {
-	return "no buildable Go source files in " + e.Dir
+	msg := "no buildable Go source files in " + e.Dir
+	if e.Ignored {
+		msg += " (.go files ignored due to build tags)"
+	}
+	return msg
 }
 
 // MultiplePackageError describes a directory containing
@@ -846,7 +851,7 @@ Found:
 		return p, badGoError
 	}
 	if len(p.GoFiles)+len(p.CgoFiles)+len(p.TestGoFiles)+len(p.XTestGoFiles) == 0 {
-		return p, &NoGoError{p.Dir}
+		return p, &NoGoError{Dir: p.Dir, Ignored: len(p.IgnoredGoFiles) > 0}
 	}
 
 	for tag := range allTags {
diff --git a/src/go/build/build_test.go b/src/go/build/build_test.go
index 198a649b15..0a20af01bd 100644
--- a/src/go/build/build_test.go
+++ b/src/go/build/build_test.go
@@ -93,6 +93,17 @@ func TestEmptyFolderImport(t *testing.T) {
 	}
 }
 
+func TestIgnoredGoFilesImport(t *testing.T) {
+	_, err := Import(".", "testdata/ignored", 0)
+	e, ok := err.(*NoGoError)
+	if !ok {
+		t.Fatal(`Import("testdata/ignored") did not return NoGoError.`)
+	}
+	if !e.Ignored {
+		t.Fatal(`Import("testdata/ignored") should have ignored Go files.`)
+	}
+}
+
 func TestMultiplePackageImport(t *testing.T) {
 	_, err := Import(".", "testdata/multi", 0)
 	mpe, ok := err.(*MultiplePackageError)
diff --git a/src/go/build/testdata/ignored/ignored.go b/src/go/build/testdata/ignored/ignored.go
new file mode 100644
index 0000000000..48a2ae88f4
--- /dev/null
+++ b/src/go/build/testdata/ignored/ignored.go
@@ -0,0 +1,3 @@
+// +build alwaysignore
+
+package ignored