diff --git a/gcc/match.pd b/gcc/match.pd
index c3b8816..3d7a0db 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -3410,6 +3410,35 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
    (bswap (bitop:c (bswap @0) @1))
    (bitop @0 (bswap @1)))))
 
+/* Recognize ((T)bswap32(x)<<32)|bswap32(x>>32) as bswap64(x).  */
+(for op (bit_ior bit_xor plus)
+  (simplify
+    (op:c
+      (lshift (convert (BUILT_IN_BSWAP32 (convert@0 @1)))
+	      INTEGER_CST@2)
+      (convert (BUILT_IN_BSWAP32 (convert@3 (rshift @1 @2)))))
+    (if (INTEGRAL_TYPE_P (type)
+	 && TYPE_PRECISION (type) == 64
+	 && types_match (TREE_TYPE (@1), uint64_type_node)
+	 && types_match (TREE_TYPE (@0), uint32_type_node)
+	 && types_match (TREE_TYPE (@3), uint32_type_node)
+	 && wi::to_widest (@2) == 32)
+      (convert (BUILT_IN_BSWAP64 @1)))))
+
+/* Recognize ((T)bswap16(x)<<16)|bswap16(x>>16) as bswap32(x).  */
+(for op (bit_ior bit_xor plus)
+  (simplify
+    (op:c
+      (lshift
+	(convert (BUILT_IN_BSWAP16 (convert (bit_and @0 INTEGER_CST@1))))
+	(INTEGER_CST@2))
+      (convert (BUILT_IN_BSWAP16 (convert (rshift @0 @2)))))
+    (if (INTEGRAL_TYPE_P (type)
+	 && TYPE_PRECISION (type) == 32
+	 && types_match (TREE_TYPE (@0), uint32_type_node)
+	 && wi::to_widest (@1) == 65535
+	 && wi::to_widest (@2) == 16)
+      (convert (BUILT_IN_BSWAP32 @0)))))
 
 /* Combine COND_EXPRs and VEC_COND_EXPRs.  */