diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_platform_limits_posix.h b/compiler-rt/lib/sanitizer_common/sanitizer_platform_limits_posix.h
--- a/compiler-rt/lib/sanitizer_common/sanitizer_platform_limits_posix.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_platform_limits_posix.h
@@ -578,8 +578,13 @@
 #endif
 
 struct __sanitizer_siginfo_pad {
+#if SANITIZER_X32
+  // x32 siginfo_t is aligned to 8 bytes.
+  u64 pad[128 / sizeof(u64)];
+#else
   // Require uptr, because siginfo_t is always pointer-size aligned on Linux.
   uptr pad[128 / sizeof(uptr)];
+#endif
 };
 
 #if SANITIZER_LINUX