diff --git a/README.md b/README.md
new file mode 100644
index 0000000..d09af26
--- /dev/null
+++ b/README.md
@@ -0,0 +1,6 @@
+# Mirrored from https://fuchsia.googlesource.com/third_party/libcxx
+
+This is a legacy mirror with the purpose of preserving the ability to build old versions of Flutter.
+
+Newer versions have already switched to https://llvm.googlesource.com/libcxx and the Fuchsia mirror
+is set to be archived and unavailable.