diff --git a/compiler-rt/lib/hwasan/hwasan_flags.inc b/compiler-rt/lib/hwasan/hwasan_flags.inc
--- a/compiler-rt/lib/hwasan/hwasan_flags.inc
+++ b/compiler-rt/lib/hwasan/hwasan_flags.inc
@@ -72,3 +72,12 @@
 HWASAN_FLAG(bool, malloc_bisect_dump, false,
             "Print all allocations within [malloc_bisect_left, "
             "malloc_bisect_right] range ")
+
+
+// Exit if we fail to enable the AArch64 kernel ABI relaxation which allows
+// tagged pointers in syscalls.  This is the default, but being able to disable
+// that behaviour is useful for running the testsuite on more platforms (the
+// testsuite can run since we manually ensure any pointer arguments to syscalls
+// are untagged before the call.
+HWASAN_FLAG(bool, fail_without_syscall_abi, true,
+	    "Exit if fail to request relaxed syscall ABI.");
diff --git a/compiler-rt/lib/hwasan/hwasan_linux.cpp b/compiler-rt/lib/hwasan/hwasan_linux.cpp
--- a/compiler-rt/lib/hwasan/hwasan_linux.cpp
+++ b/compiler-rt/lib/hwasan/hwasan_linux.cpp
@@ -119,8 +119,10 @@
 #define PR_GET_TAGGED_ADDR_CTRL 56
 #define PR_TAGGED_ADDR_ENABLE (1UL << 0)
   // Check we're running on a kernel that can use the tagged address ABI.
-  if (internal_prctl(PR_GET_TAGGED_ADDR_CTRL, 0, 0, 0, 0) == (uptr)-1 &&
-      errno == EINVAL) {
+  int local_errno = 0;
+  if (internal_iserror(internal_prctl(PR_GET_TAGGED_ADDR_CTRL, 0, 0, 0, 0),
+                       &local_errno) &&
+      local_errno == EINVAL) {
 #if SANITIZER_ANDROID
     // Some older Android kernels have the tagged pointer ABI on
     // unconditionally, and hence don't have the tagged-addr prctl while still
@@ -129,17 +131,20 @@
     // case.
     return;
 #else
-    Printf(
-        "FATAL: "
-        "HWAddressSanitizer requires a kernel with tagged address ABI.\n");
-    Die();
+    if (flags()->fail_without_syscall_abi) {
+      Printf(
+          "FATAL: "
+          "HWAddressSanitizer requires a kernel with tagged address ABI.\n");
+      Die();
+    }
 #endif
   }
 
   // Turn on the tagged address ABI.
-  if (internal_prctl(PR_SET_TAGGED_ADDR_CTRL, PR_TAGGED_ADDR_ENABLE, 0, 0, 0) ==
-          (uptr)-1 ||
-      !internal_prctl(PR_GET_TAGGED_ADDR_CTRL, 0, 0, 0, 0)) {
+  if ((internal_iserror(internal_prctl(PR_SET_TAGGED_ADDR_CTRL,
+                                       PR_TAGGED_ADDR_ENABLE, 0, 0, 0)) ||
+       !internal_prctl(PR_GET_TAGGED_ADDR_CTRL, 0, 0, 0, 0)) &&
+      flags()->fail_without_syscall_abi) {
     Printf(
         "FATAL: HWAddressSanitizer failed to enable tagged address syscall "
         "ABI.\nSuggest check `sysctl abi.tagged_addr_disabled` "
diff --git a/compiler-rt/test/hwasan/lit.cfg.py b/compiler-rt/test/hwasan/lit.cfg.py
--- a/compiler-rt/test/hwasan/lit.cfg.py
+++ b/compiler-rt/test/hwasan/lit.cfg.py
@@ -38,7 +38,7 @@
 config.substitutions.append( ("%clangxx_hwasan_oldrt ", build_invocation(clang_hwasan_oldrt_cxxflags)) )
 config.substitutions.append( ("%compiler_rt_libdir", config.compiler_rt_libdir) )
 
-default_hwasan_opts_str = ':'.join(['disable_allocator_tagging=1', 'random_tags=0'] + config.default_sanitizer_opts)
+default_hwasan_opts_str = ':'.join(['disable_allocator_tagging=1', 'random_tags=0', 'fail_without_syscall_abi=0'] + config.default_sanitizer_opts)
 if default_hwasan_opts_str:
   config.environment['HWASAN_OPTIONS'] = default_hwasan_opts_str
   default_hwasan_opts_str += ':'