Index: lib/Support/Unix/Path.inc
===================================================================
--- lib/Support/Unix/Path.inc
+++ lib/Support/Unix/Path.inc
@@ -424,6 +424,9 @@
 #elif defined(__Fuchsia__)
   // Fuchsia doesn't yet support remote filesystem mounts.
   return true;
+#elif defined(__EMSCRIPTEN__)
+  // Emscripten doesn't currently support remote filesystem mounts.
+  return true;
 #elif defined(__HAIKU__)
   // Haiku doesn't expose this information.
   return false;