--- a/gcc/c/c-parser.c
+++ b/gcc/c/c-parser.c
@@ -224,6 +224,9 @@ struct GTY(()) c_parser {
   /* Buffer to hold all the tokens from parsing the vector attribute for the
      SIMD-enabled functions (formerly known as elemental functions).  */
   vec <c_token, va_gc> *cilk_simd_fn_tokens;
+
+  /* Designates if "simd" attribute is specified in decl.  */
+  BOOL_BITFIELD simd_attr_present : 1;
 };
 
 
@@ -1701,7 +1704,8 @@ c_parser_declaration_or_fndef (c_parser *parser, bool fndef_ok,
       if (declarator == NULL)
 	{
 	  if (omp_declare_simd_clauses.exists ()
-	      || !vec_safe_is_empty (parser->cilk_simd_fn_tokens))
+	      || !vec_safe_is_empty (parser->cilk_simd_fn_tokens)
+	      || parser->simd_attr_present)
 	    c_finish_omp_declare_simd (parser, NULL_TREE, NULL_TREE,
 				       omp_declare_simd_clauses);
 	  c_parser_skip_to_end_of_block_or_statement (parser);
@@ -1797,7 +1801,8 @@ c_parser_declaration_or_fndef (c_parser *parser, bool fndef_ok,
 		  if (!d)
 		    d = error_mark_node;
 		  if (omp_declare_simd_clauses.exists ()
-		      || !vec_safe_is_empty (parser->cilk_simd_fn_tokens))
+		      || !vec_safe_is_empty (parser->cilk_simd_fn_tokens)
+		      || parser->simd_attr_present)
 		    c_finish_omp_declare_simd (parser, d, NULL_TREE,
 					       omp_declare_simd_clauses);
 		}
@@ -1810,7 +1815,8 @@ c_parser_declaration_or_fndef (c_parser *parser, bool fndef_ok,
 		  if (!d)
 		    d = error_mark_node;
 		  if (omp_declare_simd_clauses.exists ()
-		      || !vec_safe_is_empty (parser->cilk_simd_fn_tokens))
+		      || !vec_safe_is_empty (parser->cilk_simd_fn_tokens)
+		      || parser->simd_attr_present)
 		    c_finish_omp_declare_simd (parser, d, NULL_TREE,
 					       omp_declare_simd_clauses);
 		  start_init (d, asm_name, global_bindings_p ());
@@ -1839,7 +1845,8 @@ c_parser_declaration_or_fndef (c_parser *parser, bool fndef_ok,
 				   chainon (postfix_attrs,
 					    all_prefix_attrs));
 	      if (omp_declare_simd_clauses.exists ()
-		  || !vec_safe_is_empty (parser->cilk_simd_fn_tokens))
+		  || !vec_safe_is_empty (parser->cilk_simd_fn_tokens)
+		  || parser->simd_attr_present)
 		{
 		  tree parms = NULL_TREE;
 		  if (d && TREE_CODE (d) == FUNCTION_DECL)
@@ -1968,7 +1975,8 @@ c_parser_declaration_or_fndef (c_parser *parser, bool fndef_ok,
 				       true, false, NULL, vNULL);
       store_parm_decls ();
       if (omp_declare_simd_clauses.exists ()
-	  || !vec_safe_is_empty (parser->cilk_simd_fn_tokens))
+	  || !vec_safe_is_empty (parser->cilk_simd_fn_tokens)
+	  || parser->simd_attr_present)
 	c_finish_omp_declare_simd (parser, current_function_decl, NULL_TREE,
 				   omp_declare_simd_clauses);
       DECL_STRUCT_FUNCTION (current_function_decl)->function_start_locus
@@ -3993,6 +4001,15 @@ c_parser_attributes (c_parser *parser)
 		break;
 	      continue;
 	    }
+	  if (is_attribute_p ("simd", attr_name))
+	    {
+	      parser->simd_attr_present = 1;
+	      c_parser_consume_token (parser);
+	      /* If the next token isn't a comma, we're done.  */
+	      if (!c_parser_next_token_is (parser, CPP_COMMA))
+		break;
+	      continue;
+	    }
 	  c_parser_consume_token (parser);
 	  if (c_parser_next_token_is_not (parser, CPP_OPEN_PAREN))
 	    {
@@ -15388,9 +15405,10 @@ c_finish_omp_declare_simd (c_parser *parser, tree fndecl, tree parms,
 			   vec<c_token> clauses)
 {
   if (flag_cilkplus
-      && clauses.exists () && !vec_safe_is_empty (parser->cilk_simd_fn_tokens))
+      && (clauses.exists () || parser->simd_attr_present)
+      && !vec_safe_is_empty (parser->cilk_simd_fn_tokens))
     {
-      error ("%<#pragma omp declare simd%> cannot be used in the same "
+      error ("%<#pragma omp declare simd%> or __simd__ attribute cannot be used in the same "
 	     "function marked as a Cilk Plus SIMD-enabled function");
       vec_free (parser->cilk_simd_fn_tokens);
       return;
@@ -15423,7 +15441,7 @@ c_finish_omp_declare_simd (c_parser *parser, tree fndecl, tree parms,
   unsigned int tokens_avail = parser->tokens_avail;
   gcc_assert (parser->tokens == &parser->tokens_buf[0]);
   bool is_cilkplus_cilk_simd_fn = false;
-  
+ 
   if (flag_cilkplus && !vec_safe_is_empty (parser->cilk_simd_fn_tokens))
     {
       parser->tokens = parser->cilk_simd_fn_tokens->address ();
@@ -15435,41 +15453,63 @@ c_finish_omp_declare_simd (c_parser *parser, tree fndecl, tree parms,
       parser->tokens = clauses.address ();
       parser->tokens_avail = clauses.length ();
     }
-  
-  /* c_parser_omp_declare_simd pushed 2 extra CPP_EOF tokens at the end.  */
-  while (parser->tokens_avail > 3)
+
+  if (parser->simd_attr_present
+      && is_cilkplus_cilk_simd_fn)
     {
-      c_token *token = c_parser_peek_token (parser);
-      if (!is_cilkplus_cilk_simd_fn) 
-	gcc_assert (token->type == CPP_NAME 
-		    && strcmp (IDENTIFIER_POINTER (token->value), "simd") == 0);
-      else
-	gcc_assert (token->type == CPP_NAME
-		    && is_cilkplus_vector_p (token->value));
-      c_parser_consume_token (parser);
-      parser->in_pragma = true;
+      error ("SIMD-enabled function attributes"
+	     "are allowed when attribute __simd__ is specified");
+      clauses[0].type = CPP_EOF;
+      return;
+    }
 
+  /* Attach `omp declare simd’ attribute if __simd__ is specified AND no OpenMP clauses
+     present in decl.  */
+  if (parser->simd_attr_present
+      && parser->tokens_avail == 0)
+    {
       tree c = NULL_TREE;
-      if (is_cilkplus_cilk_simd_fn) 
-	c = c_parser_omp_all_clauses (parser, CILK_SIMD_FN_CLAUSE_MASK,
-				      "SIMD-enabled functions attribute");
-      else 
-	c = c_parser_omp_all_clauses (parser, OMP_DECLARE_SIMD_CLAUSE_MASK,
-				      "#pragma omp declare simd");
-      c = c_omp_declare_simd_clauses_to_numbers (parms, c);
-      if (c != NULL_TREE)
-	c = tree_cons (NULL_TREE, c, NULL_TREE);
-      if (is_cilkplus_cilk_simd_fn) 
-	{ 
-	  tree k = build_tree_list (get_identifier ("cilk simd function"), 
-				    NULL_TREE);
-	  TREE_CHAIN (k) = DECL_ATTRIBUTES (fndecl);
-	  DECL_ATTRIBUTES (fndecl) = k;
-	} 
       c = build_tree_list (get_identifier ("omp declare simd"), c);
       TREE_CHAIN (c) = DECL_ATTRIBUTES (fndecl);
       DECL_ATTRIBUTES (fndecl) = c;
     }
+  else
+    {
+      /* c_parser_omp_declare_simd pushed 2 extra CPP_EOF tokens at the end.  */
+      while (parser->tokens_avail > 3)
+	{
+	  c_token *token = c_parser_peek_token (parser);
+	  if (!is_cilkplus_cilk_simd_fn)
+	    gcc_assert (token->type == CPP_NAME
+			&& strcmp (IDENTIFIER_POINTER (token->value), "simd") == 0);
+	  else
+	    gcc_assert (token->type == CPP_NAME
+			&& is_cilkplus_vector_p (token->value));
+	  c_parser_consume_token (parser);
+	  parser->in_pragma = true;
+
+	  tree c = NULL_TREE;
+	  if (is_cilkplus_cilk_simd_fn)
+	    c = c_parser_omp_all_clauses (parser, CILK_SIMD_FN_CLAUSE_MASK,
+					  "SIMD-enabled functions attribute");
+	  else
+	    c = c_parser_omp_all_clauses (parser, OMP_DECLARE_SIMD_CLAUSE_MASK,
+					  "#pragma omp declare simd");
+	  c = c_omp_declare_simd_clauses_to_numbers (parms, c);
+	  if (c != NULL_TREE)
+	    c = tree_cons (NULL_TREE, c, NULL_TREE);
+	  if (is_cilkplus_cilk_simd_fn)
+	    {
+	      tree k = build_tree_list (get_identifier ("cilk simd function"),
+					NULL_TREE);
+	      TREE_CHAIN (k) = DECL_ATTRIBUTES (fndecl);
+	      DECL_ATTRIBUTES (fndecl) = k;
+	    }
+	  c = build_tree_list (get_identifier ("omp declare simd"), c);
+	  TREE_CHAIN (c) = DECL_ATTRIBUTES (fndecl);
+	  DECL_ATTRIBUTES (fndecl) = c;
+	}
+    }
 
   parser->tokens = &parser->tokens_buf[0];
   parser->tokens_avail = tokens_avail;
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 7555bf3..69ffb61 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -19331,7 +19331,9 @@ cp_parser_late_return_type_opt (cp_parser* parser, cp_declarator *declarator,
   /* A late-specified return type is indicated by an initial '->'. */
   if (token->type != CPP_DEREF
       && token->keyword != RID_REQUIRES
-      && !(declare_simd_p || cilk_simd_fn_vector_p))
+      && !(declare_simd_p
+	   || cilk_simd_fn_vector_p
+	   || parser->simd_attr_present))
     return NULL_TREE;
 
   tree save_ccp = current_class_ptr;
@@ -19363,6 +19365,18 @@ cp_parser_late_return_type_opt (cp_parser* parser, cp_declarator *declarator,
       = cp_parser_late_parsing_omp_declare_simd (parser,
 						 declarator->std_attributes);
 
+  if (parser->simd_attr_present
+      && !declare_simd_p)
+    {
+      if (cilk_simd_fn_vector_p)
+	error ("__simd__ attribute cannot be used in the same function"
+	       " marked as a Cilk Plus SIMD-enabled function");
+
+      tree c = build_tree_list (get_identifier ("omp declare simd"), NULL_TREE);
+      TREE_CHAIN (c) = declarator->std_attributes;
+      declarator->std_attributes = c;
+    }
+
   if (quals >= 0)
     {
       current_class_ptr = save_ccp;
@@ -23320,6 +23334,21 @@ cp_parser_gnu_attribute_list (cp_parser* parser)
 	  else if (is_cilkplus_vector_p (identifier))
 	    {
 	      cp_parser_cilk_simd_fn_vector_attrs (parser, id_token);
+	      /* Now, look for more attributes.  If the next token isn't a
+		 `,', we're done.  */
+	      if (token->type != CPP_COMMA)
+		break;
+
+	      continue;
+	    } else
+	  if (is_attribute_p ("simd", identifier))
+	    {
+	      parser->simd_attr_present = 1;
+	      /* Now, look for more attributes.  If the next token isn't a
+		 `,', we're done.  */
+	      if (token->type != CPP_COMMA)
+		break;
+
 	      continue;
 	    }
 
diff --git a/gcc/cp/parser.h b/gcc/cp/parser.h
index 760467c..f4e33e3 100644
--- a/gcc/cp/parser.h
+++ b/gcc/cp/parser.h
@@ -371,6 +371,8 @@ struct GTY(()) cp_parser {
      necessary.  */
   cp_omp_declare_simd_data * GTY((skip)) cilk_simd_fn_info;
 
+  bool simd_attr_present;
+
   /* Nonzero if parsing a parameter list where 'auto' should trigger an implicit
      template parameter.  */
   bool auto_is_implicit_function_template_parm_p;
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index fdb1547..32994a2 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -3066,6 +3066,21 @@ This function attribute make a stack protection of the function if
 flags @option{fstack-protector} or @option{fstack-protector-strong}
 or @option{fstack-protector-explicit} are set.
 
+@item simd
+@cindex @code{simd} function attribute.
+This attribute enables creation of one or more function versions that
+can process multiple arguments using SIMD instructions from a
+single invocation.  Specifying this attribute allows compiler to
+assume that such a versions are available at link time (provided
+in the same or another translation unit).  Generated versions are
+target dependent and described in corresponding Vector ABI document.  For
+x86_64 target this document can be found
+@w{@uref{https://sourceware.org/glibc/wiki/libmvec?action=AttachFile&do=view&target=VectorABI.txt,here}}.
+It is prohibited to use the attribute along with Cilk Plus's @code{vector}
+attribute. If the attribute is specified and @code{#pragma omp declare simd}
+presented on a declaration and @code{-fopenmp} or @code{-fopenmp-simd}
+switch is specified, then the attribute is ignored.
+
 @item target (@var{options})
 @cindex @code{target} function attribute
 Multiple target back ends implement the @code{target} attribute
diff --git a/gcc/omp-low.c b/gcc/omp-low.c
index ad7c017..232dc5c 100644
--- a/gcc/omp-low.c
+++ b/gcc/omp-low.c
@@ -17412,10 +17412,7 @@ public:
 bool
 pass_omp_simd_clone::gate (function *)
 {
-  return ((flag_openmp || flag_openmp_simd
-	   || flag_cilkplus
-	   || (in_lto_p && !flag_wpa))
-	  && (targetm.simd_clone.compute_vecsize_and_simdlen != NULL));
+  return targetm.simd_clone.compute_vecsize_and_simdlen != NULL;
 }
 
 } // anon namespace
diff --git a/gcc/testsuite/c-c++-common/attr-simd-2.c b/gcc/testsuite/c-c++-common/attr-simd-2.c
new file mode 100644
index 0000000..e9afc11
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/attr-simd-2.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-fdump-tree-optimized -fopenmp-simd" } */
+
+#pragma omp declare simd
+__attribute__((__simd__))
+static int simd_attr (void)
+{
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump "omp declare simd" "optimized" } } */
diff --git a/gcc/testsuite/c-c++-common/attr-simd-3.c b/gcc/testsuite/c-c++-common/attr-simd-3.c
new file mode 100644
index 0000000..2bbdf04
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/attr-simd-3.c
@@ -0,0 +1,5 @@
+/* { dg-do compile } */
+/* { dg-options "-fcilkplus" } */
+/* { dg-prune-output "undeclared here \\(not in a function\\)|\[^\n\r\]* was not declared in this scope" } */
+
+void f () __attribute__((__simd__, __vector__)); /* { dg-error "in the same function marked as a Cilk Plus" } */
diff --git a/gcc/testsuite/c-c++-common/attr-simd.c b/gcc/testsuite/c-c++-common/attr-simd.c
new file mode 100644
index 0000000..dabdd81
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/attr-simd.c
@@ -0,0 +1,10 @@
+/* { dg-do compile } */
+/* { dg-options "-fdump-tree-optimized" } */
+
+__attribute__((__simd__))
+static int simd_attr (void)
+{
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump "omp declare simd" "optimized" } } */
