diff -up ./pr/include/md/_linux.h.gcc-atomics ./pr/include/md/_linux.h
--- ./pr/include/md/_linux.h.gcc-atomics	2022-09-20 11:23:22.008942926 -0700
+++ ./pr/include/md/_linux.h	2022-09-20 11:34:45.536751340 -0700
@@ -105,6 +105,15 @@
 #endif
 
 #if defined(__i386__)
+#if defined(__GNUC__)
+/* Use GCC built-in functions */
+#define _PR_HAVE_ATOMIC_OPS
+#define _MD_INIT_ATOMIC()
+#define _MD_ATOMIC_INCREMENT(ptr) __sync_add_and_fetch(ptr, 1)
+#define _MD_ATOMIC_DECREMENT(ptr) __sync_sub_and_fetch(ptr, 1)
+#define _MD_ATOMIC_ADD(ptr, i) __sync_add_and_fetch(ptr, i)
+#define _MD_ATOMIC_SET(ptr, nv) __sync_lock_test_and_set(ptr, nv)
+#else
 #define _PR_HAVE_ATOMIC_OPS
 #define _MD_INIT_ATOMIC()
 extern PRInt32 _PR_x86_AtomicIncrement(PRInt32 *val);
@@ -116,6 +125,7 @@ extern PRInt32 _PR_x86_AtomicAdd(PRInt32
 extern PRInt32 _PR_x86_AtomicSet(PRInt32 *val, PRInt32 newval);
 #define _MD_ATOMIC_SET                _PR_x86_AtomicSet
 #endif
+#endif
 
 #if defined(__ia64__)
 #define _PR_HAVE_ATOMIC_OPS
@@ -131,6 +141,15 @@ extern PRInt32 _PR_ia64_AtomicSet(PRInt3
 #endif
 
 #if defined(__x86_64__)
+#if defined(__GNUC__)
+/* Use GCC built-in functions */
+#define _PR_HAVE_ATOMIC_OPS
+#define _MD_INIT_ATOMIC()
+#define _MD_ATOMIC_INCREMENT(ptr) __sync_add_and_fetch(ptr, 1)
+#define _MD_ATOMIC_DECREMENT(ptr) __sync_sub_and_fetch(ptr, 1)
+#define _MD_ATOMIC_ADD(ptr, i) __sync_add_and_fetch(ptr, i)
+#define _MD_ATOMIC_SET(ptr, nv) __sync_lock_test_and_set(ptr, nv)
+#else
 #define _PR_HAVE_ATOMIC_OPS
 #define _MD_INIT_ATOMIC()
 extern PRInt32 _PR_x86_64_AtomicIncrement(PRInt32 *val);
@@ -142,6 +161,7 @@ extern PRInt32 _PR_x86_64_AtomicAdd(PRIn
 extern PRInt32 _PR_x86_64_AtomicSet(PRInt32 *val, PRInt32 newval);
 #define _MD_ATOMIC_SET                _PR_x86_64_AtomicSet
 #endif
+#endif
 
 #if defined(__loongarch__)
 #if defined(__GNUC__)