--- a/libcxxabi/test/test_fallback_malloc.pass.cpp	Wed Jul 21 10:27:27 2021 +0900
+++ b/libcxxabi/test/test_fallback_malloc.pass.cpp	Wed Nov 09 17:45:10 2022 +0900
@@ -1,4 +1,4 @@
-//===--------------------- test_fallback_malloc.cpp -----------------------===//
+//===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
@@ -8,21 +8,36 @@
 
 #include <cstdio>
 #include <deque>
+#include <cassert>
 
 #include <__threading_support>
 
+// UNSUPPORTED: c++03
+// UNSUPPORTED: modules-build && no-threads
+
+// Necessary because we include a private source file of libc++abi, which
+// only understands _LIBCXXABI_HAS_NO_THREADS.
+#include "test_macros.h"
+#ifdef TEST_HAS_NO_THREADS
+# define _LIBCXXABI_HAS_NO_THREADS
+#endif
+
 typedef std::deque<void *> container;
 
 // #define  DEBUG_FALLBACK_MALLOC
 #define INSTRUMENT_FALLBACK_MALLOC
 #include "../src/fallback_malloc.cpp"
 
+void assertAlignment(void* ptr) { assert(reinterpret_cast<size_t>(ptr) % alignof(FallbackMaxAlignType) == 0); }
+
 container alloc_series ( size_t sz ) {
     container ptrs;
     void *p;
 
-    while ( NULL != ( p = fallback_malloc ( sz )))
-        ptrs.push_back ( p );
+    while (NULL != (p = fallback_malloc(sz))) {
+      assertAlignment(p);
+      ptrs.push_back(p);
+    }
     return ptrs;
 }
 
@@ -31,8 +46,9 @@
     void *p;
 
     while ( NULL != ( p = fallback_malloc ( sz ))) {
-        ptrs.push_back ( p );
-        sz *= growth;
+      assertAlignment(p);
+      ptrs.push_back(p);
+      sz *= growth;
     }
 
     return ptrs;
@@ -46,6 +62,7 @@
     for ( const size_t *iter = first; iter != last; ++iter ) {
         if ( NULL == (p = fallback_malloc ( *iter )))
             break;
+        assertAlignment(p);
         ptrs.push_back ( p );
     }