diff --git a/src/cmd/dist/test.go b/src/cmd/dist/test.go
index bc1f7339a2..fe9dcc216e 100644
--- a/src/cmd/dist/test.go
+++ b/src/cmd/dist/test.go
@@ -133,7 +133,11 @@ func (t *tester) run() {
 	// to break if we don't automatically refresh things here.
 	// Rebuilding is a shortened bootstrap.
 	// See cmdbootstrap for a description of the overall process.
-	if !t.listMode {
+	//
+	// But don't do this if we're running in the Go build system,
+	// where cmd/dist is invoked many times. This just slows that
+	// down (Issue 24300).
+	if !t.listMode && os.Getenv("GO_BUILDER_NAME") == "" {
 		goInstall("go", append([]string{"-i"}, toolchain...)...)
 		goInstall("go", append([]string{"-i"}, toolchain...)...)
 		goInstall("go", "std", "cmd")