diff --git a/libgomp/libgomp.h b/libgomp/libgomp.h
index 33a9591285f..023d8a8c1df 100644
--- a/libgomp/libgomp.h
+++ b/libgomp/libgomp.h
@@ -257,6 +257,30 @@ struct gomp_doacross_work_share
   unsigned int shift_counts[];
 };
 
+/* Like struct gomp_work_share, but only the 1st cacheline of it plus
+   flexible array at the end.
+   Keep in sync with struct gomp_work_share.  */
+struct gomp_work_share_1st_cacheline
+{
+  enum gomp_schedule_type sched;
+  int mode;
+  union {
+    struct {
+      long chunk_size, end, incr;
+    };
+    struct {
+      unsigned long long chunk_size_ull, end_ull, incr_ull;
+    };
+  };
+  union {
+    unsigned *ordered_team_ids;
+    struct gomp_doacross_work_share *doacross;
+  };
+  unsigned ordered_num_used, ordered_owner, ordered_cur;
+  struct gomp_work_share *next_alloc;
+  char pad[];
+};
+
 struct gomp_work_share
 {
   /* This member records the SCHEDULE clause to be used for this construct.
@@ -324,7 +348,12 @@ struct gomp_work_share
      are in a different cache line.  */
 
   /* This lock protects the update of the following members.  */
+#ifdef GOMP_HAVE_EFFICIENT_ALIGNED_ALLOC
   gomp_mutex_t lock __attribute__((aligned (64)));
+#else
+  char pad[64 - offsetof (struct gomp_work_share_1st_cacheline, pad)];
+  gomp_mutex_t lock;
+#endif
 
   /* This is the count of the number of threads that have exited the work
      share construct.  If the construct was marked nowait, they have moved on
@@ -362,6 +391,12 @@ struct gomp_work_share
   unsigned inline_ordered_team_ids[0];
 };
 
+extern char gomp_workshare_struct_check1
+  [offsetof (struct gomp_work_share_1st_cacheline, next_alloc)
+   == offsetof (struct gomp_work_share, next_alloc) ? 1 : -1];
+extern char gomp_workshare_struct_check2
+  [offsetof (struct gomp_work_share, lock) == 64 ? 1 : -1];
+
 /* This structure contains all of the thread-local data associated with 
    a thread team.  This is the data that must be saved when a thread
    encounters a nested PARALLEL construct.  */
diff --git a/libgomp/work.c b/libgomp/work.c
index 9d63eec9832..bf2559155f1 100644
--- a/libgomp/work.c
+++ b/libgomp/work.c
@@ -191,7 +191,12 @@ gomp_work_share_start (size_t ordered)
   /* Work sharing constructs can be orphaned.  */
   if (team == NULL)
     {
+#ifdef GOMP_HAVE_EFFICIENT_ALIGNED_ALLOC
+      ws = gomp_aligned_alloc (__alignof (struct gomp_work_share),
+			       sizeof (*ws));
+#else
       ws = gomp_malloc (sizeof (*ws));
+#endif
       gomp_init_work_share (ws, ordered, 1);
       thr->ts.work_share = ws;
       return true;