diff --git a/gcc/doc/md.texi b/gcc/doc/md.texi
index bca0d8f..bbb12bb 100644
--- a/gcc/doc/md.texi
+++ b/gcc/doc/md.texi
@@ -518,11 +518,12 @@ referred to more than once in a single template that generates multiple
 assembler instructions.
 
 @samp{%} followed by a punctuation character specifies a substitution that
-does not use an operand.  Only one case is standard: @samp{%%} outputs a
-@samp{%} into the assembler code.  Other nonstandard cases can be
-defined in the @code{PRINT_OPERAND} macro.  You must also define
-which punctuation characters are valid with the
-@code{PRINT_OPERAND_PUNCT_VALID_P} macro.
+does not use an operand.  There are four standard cases: @samp{%%},
+@samp{%@{}, @samp{%@}} and @samp{%|} output @samp{%}, @samp{@{}, @samp{@}}
+and @samp{|} respectively into the assembler code.  Other nonstandard cases
+can be defined in the @code{PRINT_OPERAND} macro.  You must also define which
+punctuation characters are valid with the @code{PRINT_OPERAND_PUNCT_VALID_P}
+macro.
 
 @cindex \
 @cindex backslash
diff --git a/gcc/final.c b/gcc/final.c
index ceb688e..833b1c3 100644
--- a/gcc/final.c
+++ b/gcc/final.c
@@ -3381,6 +3381,7 @@ output_asm_operand_names (rtx *operands, int *oporder, int nops)
 static const char *
 do_assembler_dialects (const char *p, int *dialect)
 {
+  int pcts = 0;
   char c = *(p - 1);
 
   switch (c)
@@ -3398,8 +3399,14 @@ do_assembler_dialects (const char *p, int *dialect)
            DIALECT_NUMBER of strings ending with '|'.  */
         for (i = 0; i < dialect_number; i++)
           {
-            while (*p && *p != '}' && *p++ != '|')
-	      ;
+	    /* For a close brace to be the end of dialect alternatives it
+	       must not be escaped by '%', i.e. '}' must follow an even number
+	       of '%'s since %% stands for the percent sign in assembler code.  */
+            while (*p && !(*p == '}' && !(pcts % 2)) && *p++ != '|')
+	      pcts = (*(p - 1) == '%') ? pcts + 1 : 0;
+
+	    pcts = 0;
+
             if (*p == '}')
 	      break;
           }
@@ -3420,8 +3427,13 @@ do_assembler_dialects (const char *p, int *dialect)
 		  output_operand_lossage ("unterminated assembly dialect alternative");
 		  break;
 		}
+
+	      pcts = (*(p - 1) == '%') ? pcts + 1 : 0;
             }
-          while (*p++ != '}');
+	  /* Check the number of '%'s followed by '{' as in previous case.  */
+          while (!(*p++ == '}' && !(pcts % 2)));
+
+	  pcts = 0;
           *dialect = 0;
         }
       else
@@ -3515,10 +3527,10 @@ output_asm_insn (const char *templ, rtx *operands)
 
       case '%':
 	/* %% outputs a single %.  */
-	if (*p == '%')
+	if (*p == '%' || *p == '{' || *p == '}' || *p == '|')
 	  {
+	    putc (*p, asm_out_file);
 	    p++;
-	    putc (c, asm_out_file);
 	  }
 	/* %= outputs a number which is unique to each insn in the entire
 	   compilation.  This is useful for making local labels that are
diff --git a/gcc/testsuite/gcc.target/i386/asm-dialect-2.c b/gcc/testsuite/gcc.target/i386/asm-dialect-2.c
new file mode 100644
index 0000000..942f505
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/asm-dialect-2.c
@@ -0,0 +1,10 @@
+/* { dg-do compile } */
+/* { dg-options "-masm=att" } */
+
+void f()
+{
+  /* Check for escaped curly braces support.  */
+  asm volatile ("{%%%{a%}%||%%%}b}" : :);
+}
+
+/* { dg-final { scan-assembler "%{a}|\[^b\]" } } */