--- libmalloc/libmalloc-425.100.7/tests/magazine_rack.c
+++ libmalloc/libmalloc-474.0.13/tests/magazine_rack.c
@@ -9,10 +9,34 @@
 #include <darwintest.h>
 #include "magazine_testing.h"
 
+// Size of allocation to fall into each rack
+#define TINY_ALLOCATION_SZ 128
+#define SMALL_ALLOCATION_SZ 1024
+#define MEDIUM_ALLOCATION_SZ 65536
+
+#define N_HELPER_THREADS 8
+
+/*
+ * Lower the size of the allocation pool on embedded devices to prevent test timeouts
+ * / limit kills. These devices do not have a medium rack, so we should still fill
+ * multiple regions for tiny/small (~1/8 MiB per region respectively).
+ */
+#if TARGET_OS_IPHONE
+#define MAX_ALLOCATIONS_PER_THREAD (uint32_t)20000
+#else
+#define MAX_ALLOCATIONS_PER_THREAD (uint32_t)100000
+#endif
+
+static_assert((MAX_ALLOCATIONS_PER_THREAD * TINY_ALLOCATION_SZ) > (2 * TINY_REGION_SIZE), "");
+static_assert((MAX_ALLOCATIONS_PER_THREAD * SMALL_ALLOCATION_SZ) > (2 * SMALL_REGION_SIZE), "");
+#if CONFIG_MEDIUM_ALLOCATOR
+static_assert((MAX_ALLOCATIONS_PER_THREAD * MEDIUM_ALLOCATION_SZ) > (2 * MEDIUM_REGION_SIZE), "");
+#endif
+
 // Stubs
 malloc_zero_policy_t malloc_zero_policy = MALLOC_ZERO_POLICY_DEFAULT;
 
-T_GLOBAL_META(T_META_RUN_CONCURRENTLY(true));
+T_GLOBAL_META(T_META_RUN_CONCURRENTLY(false), T_META_TIMEOUT(1200));
 
 T_DECL(basic_magazine_init, "allocate magazine counts")
 {
@@ -50,16 +74,20 @@
 thread(void *arg)
 {
 	uintptr_t sz = (uintptr_t)arg;
+	uint32_t max_allocations = MAX_ALLOCATIONS_PER_THREAD;
+
 	T_LOG("thread started (allocation size: %lu bytes)\n", sz);
 	void *temp = malloc(sz);
 
 	uint64_t c = 100;
 	while (c-- > 0) {
-		uint32_t num = arc4random_uniform(100000);
+		uint32_t num = arc4random_uniform(max_allocations);
 		void **allocs = malloc(sizeof(void *) * num);
+		T_QUIET; T_ASSERT_NOTNULL(allocs, "Failed to allocate initial array with size %lu\n", num * sizeof(void *));
 
 		for (int i=0; i<num; i++) {
 			allocs[i] = malloc(sz);
+			T_QUIET; T_ASSERT_NOTNULL(allocs[i], "Failed to make allocation with size %lu\n", sz);
 		}
 		for (int i=0; i<num; i++) {
 			free(allocs[num - 1 - i]);
@@ -70,37 +98,32 @@
 	return NULL;
 }
 
-T_DECL(rack_tiny_region_remove, "exercise region deallocation race (rdar://66713029)")
+void
+test_region_remove(size_t allocation_size)
 {
+	T_LOG("Will allocate up to %u B per thread over %d threads\n", MAX_ALLOCATIONS_PER_THREAD, N_HELPER_THREADS);
 	pthread_t p1;
 	pthread_create(&p1, NULL, pressure_thread, NULL);
 
-	const int threads = 8;
-	pthread_t p[threads];
+	pthread_t p[N_HELPER_THREADS];
 
-	for (int i=0; i<threads; i++) {
-		pthread_create(&p[i], NULL, thread, (void *)128);
+	for (int i=0; i<N_HELPER_THREADS; i++) {
+		pthread_create(&p[i], NULL, thread, (void *) allocation_size);
 	}
-	for (int i=0; i<threads; i++) {
+	for (int i=0; i<N_HELPER_THREADS; i++) {
 		pthread_join(p[i], NULL);
 	}
+}
+
+T_DECL(rack_tiny_region_remove, "exercise region deallocation race (rdar://66713029)")
+{
+	test_region_remove(TINY_ALLOCATION_SZ);
 	T_PASS("finished without crashing");
 }
 
 T_DECL(rack_small_region_remove, "exercise region deallocation race (rdar://66713029)")
 {
-	pthread_t p1;
-	pthread_create(&p1, NULL, pressure_thread, NULL);
-
-	const int threads = 8;
-	pthread_t p[threads];
-
-	for (int i=0; i<threads; i++) {
-		pthread_create(&p[i], NULL, thread, (void *)1024);
-	}
-	for (int i=0; i<threads; i++) {
-		pthread_join(p[i], NULL);
-	}
+	test_region_remove(SMALL_ALLOCATION_SZ);
 	T_PASS("finished without crashing");
 }
 
@@ -109,17 +132,6 @@
 	   T_META_ENVVAR("MallocMediumActivationThreshold=1"),
 	   T_META_ENABLED(CONFIG_MEDIUM_ALLOCATOR))
 {
-	pthread_t p1;
-	pthread_create(&p1, NULL, pressure_thread, NULL);
-
-	const int threads = 8;
-	pthread_t p[threads];
-
-	for (int i=0; i<threads; i++) {
-		pthread_create(&p[i], NULL, thread, (void *)65536);
-	}
-	for (int i=0; i<threads; i++) {
-		pthread_join(p[i], NULL);
-	}
+	test_region_remove(MEDIUM_ALLOCATION_SZ);
 	T_PASS("finished without crashing");
 }