Index: test/tools/lldb-gdbserver/main.cpp
===================================================================
--- test/tools/lldb-gdbserver/main.cpp
+++ test/tools/lldb-gdbserver/main.cpp
@@ -20,6 +20,10 @@
 #include <sys/syscall.h>
 #endif
 
+#if defined(__linux__)
+#include <sys/prctl.h>
+#endif
+
 static const char *const RETVAL_PREFIX               = "retval:";
 static const char *const SLEEP_PREFIX                = "sleep:";
 static const char *const STDERR_PREFIX               = "stderr:";
@@ -206,6 +210,17 @@
 
 int main (int argc, char **argv)
 {
+#if defined(__linux__)
+    // Immediately enable any ptracer so that we can allow the stub attach
+    // operation to succeed.  Some Linux kernels are locked down so that
+    // only an ancestor can be a ptracer of a process.  This disables that
+    // restriction.  Without it, attach-related stub tests will fail.
+#if defined(PR_SET_PTRACER) && defined(PR_SET_PTRACER_ANY)
+    const int prctl_result = prctl(PR_SET_PTRACER, PR_SET_PTRACER_ANY, 0, 0, 0);
+    static_cast<void> (prctl_result);
+#endif
+#endif
+
 	std::vector<pthread_t> threads;
 	std::unique_ptr<uint8_t[]> heap_array_up;
     int return_value = 0;