http://www.databaseusers.com/article/6047407/Bug%3A+Build+failure+on+Linux+with+clang+libc%2B%2B+(atomic+issues)
https://gist.githubusercontent.com/LnL7/5153b251fd525fe15de69b67e63a6075/raw/7778e9364679093a32dec2908656738e16b6bdcb/clang.patch

diff --git dbinc/atomic.h dbinc/atomic.h
index 6a858f7..9f338dc 100644
--- dbinc/atomic.h
+++ dbinc/atomic.h
@@ -70,7 +70,7 @@ typedef struct {
  * These have no memory barriers; the caller must include them when necessary.
  */
 #define	atomic_read(p)		((p)->value)
-#define	atomic_init(p, val)	((p)->value = (val))
+#define	atomic_init_db(p, val)	((p)->value = (val))
 
 #ifdef HAVE_ATOMIC_SUPPORT
 
@@ -144,7 +144,7 @@ typedef LONG volatile *interlocked_val;
 #define	atomic_inc(env, p)	__atomic_inc(p)
 #define	atomic_dec(env, p)	__atomic_dec(p)
 #define	atomic_compare_exchange(env, p, o, n)	\
-	__atomic_compare_exchange((p), (o), (n))
+	__atomic_compare_exchange_db((p), (o), (n))
 static inline int __atomic_inc(db_atomic_t *p)
 {
 	int	temp;
@@ -176,7 +176,7 @@ static inline int __atomic_dec(db_atomic_t *p)
  * http://gcc.gnu.org/onlinedocs/gcc-4.1.0/gcc/Atomic-Builtins.html
  * which configure could be changed to use.
  */
-static inline int __atomic_compare_exchange(
+static inline int __atomic_compare_exchange_db(
 	db_atomic_t *p, atomic_value_t oldval, atomic_value_t newval)
 {
 	atomic_value_t was;
@@ -206,7 +206,7 @@ static inline int __atomic_compare_exchange(
 #define	atomic_dec(env, p)	(--(p)->value)
 #define	atomic_compare_exchange(env, p, oldval, newval)		\
 	(DB_ASSERT(env, atomic_read(p) == (oldval)),		\
-	atomic_init(p, (newval)), 1)
+	atomic_init_db(p, (newval)), 1)
 #else
 #define atomic_inc(env, p)	__atomic_inc(env, p)
 #define atomic_dec(env, p)	__atomic_dec(env, p)
diff --git mp/mp_fget.c mp/mp_fget.c
index 16de695..d0dcc29 100644
--- mp/mp_fget.c
+++ mp/mp_fget.c
@@ -617,7 +617,7 @@
 
 		/* Initialize enough so we can call __memp_bhfree. */
 		alloc_bhp->flags = 0;
-		atomic_init(&alloc_bhp->ref, 1);
+		atomic_init_db(&alloc_bhp->ref, 1);
 #ifdef DIAGNOSTIC
 		if ((uintptr_t)alloc_bhp->buf & (sizeof(size_t) - 1)) {
 			__db_errx(env,
@@ -911,7 +911,7 @@
 			MVCC_MPROTECT(bhp->buf, mfp->stat.st_pagesize,
 			    PROT_READ);
 
-		atomic_init(&alloc_bhp->ref, 1);
+		atomic_init_db(&alloc_bhp->ref, 1);
 		MUTEX_LOCK(env, alloc_bhp->mtx_buf);
 		alloc_bhp->priority = bhp->priority;
 		alloc_bhp->pgno = bhp->pgno;
diff --git mp/mp_mvcc.c mp/mp_mvcc.c
index 770bad8..e28cce0 100644
--- mp/mp_mvcc.c
+++ mp/mp_mvcc.c
@@ -276,7 +276,7 @@ __memp_bh_freeze(dbmp, infop, hp, bhp, need_frozenp)
 #else
 	memcpy(frozen_bhp, bhp, SSZA(BH, buf));
 #endif
-	atomic_init(&frozen_bhp->ref, 0);
+	atomic_init_db(&frozen_bhp->ref, 0);
 	if (mutex != MUTEX_INVALID)
 		frozen_bhp->mtx_buf = mutex;
 	else if ((ret = __mutex_alloc(env, MTX_MPOOL_BH,
@@ -428,7 +428,7 @@ __memp_bh_thaw(dbmp, infop, hp, frozen_bhp, alloc_bhp)
 #endif
 		alloc_bhp->mtx_buf = mutex;
 		MUTEX_LOCK(env, alloc_bhp->mtx_buf);
-		atomic_init(&alloc_bhp->ref, 1);
+		atomic_init_db(&alloc_bhp->ref, 1);
 		F_CLR(alloc_bhp, BH_FROZEN);
 	}
 
diff --git mp/mp_region.c mp/mp_region.c
index 4952030..47645f8 100644
--- mp/mp_region.c
+++ mp/mp_region.c
@@ -224,7 +224,7 @@
 			     MTX_MPOOL_FILE_BUCKET, 0, &htab[i].mtx_hash)) != 0)
 				return (ret);
 			SH_TAILQ_INIT(&htab[i].hash_bucket);
-			atomic_init(&htab[i].hash_page_dirty, 0);
+			atomic_init_db(&htab[i].hash_page_dirty, 0);
 		}
 
 		/*
@@ -269,7 +269,7 @@
 		hp->mtx_hash = (mtx_base == MUTEX_INVALID) ? MUTEX_INVALID :
 		    mtx_base + i;
 		SH_TAILQ_INIT(&hp->hash_bucket);
-		atomic_init(&hp->hash_page_dirty, 0);
+		atomic_init_db(&hp->hash_page_dirty, 0);
 #ifdef HAVE_STATISTICS
 		hp->hash_io_wait = 0;
 		hp->hash_frozen = hp->hash_thawed = hp->hash_frozen_freed = 0;
diff --git mutex/mut_method.c mutex/mut_method.c
index 09353b0..177353c 100644
--- mutex/mut_method.c
+++ mutex/mut_method.c
@@ -426,7 +426,7 @@
 	MUTEX_LOCK(env, mtx);
 	ret = atomic_read(v) == oldval;
 	if (ret)
-		atomic_init(v, newval);
+		atomic_init_db(v, newval);
 	MUTEX_UNLOCK(env, mtx);
 
 	return (ret);
diff --git mutex/mut_tas.c mutex/mut_tas.c
index 106b161..fc4de9d 100644
--- mutex/mut_tas.c
+++ mutex/mut_tas.c
@@ -46,7 +46,7 @@
 
 #ifdef HAVE_SHARED_LATCHES
 	if (F_ISSET(mutexp, DB_MUTEX_SHARED))
-		atomic_init(&mutexp->sharecount, 0);
+		atomic_init_db(&mutexp->sharecount, 0);
 	else
 #endif
 	if (MUTEX_INIT(&mutexp->tas)) {
@@ -486,7 +486,7 @@
 			F_CLR(mutexp, DB_MUTEX_LOCKED);
 			/* Flush flag update before zeroing count */
 			MEMBAR_EXIT();
-			atomic_init(&mutexp->sharecount, 0);
+			atomic_init_db(&mutexp->sharecount, 0);
 		} else {
 			DB_ASSERT(env, sharecount > 0);
 			MEMBAR_EXIT();