Index: compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp
===================================================================
--- compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp
+++ compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp
@@ -162,6 +162,12 @@
   // on any thread, setuid call hangs.
   // See test/sanitizer_common/TestCases/Linux/setuid.c.
   internal_sigdelset(&set, 33);
+#  endif
+#  if SANITIZER_LINUX
+  // Seccomp-BPF-sandboxed processes rely on SIGSYS to handle trapped syscalls.
+  // If this signal is blocked, such calls cannot be handled and the process may
+  // hang.
+  internal_sigdelset(&set, 31);
 #  endif
   SetSigProcMask(&set, &saved_);
   if (copy)