diff --git a/src/edit.c b/src/edit.c
index ebecdb6..82e2b3b 100644
--- a/src/edit.c
+++ b/src/edit.c
@@ -5847,7 +5847,7 @@
 	 * Need to remove existing (middle) comment leader and insert end
 	 * comment leader.  First, check what comment leader we can find.
 	 */
-	i = get_leader_len(line = ml_get_curline(), &p, FALSE);
+	i = get_leader_len(line = ml_get_curline(), &p, FALSE, TRUE);
 	if (i > 0 && vim_strchr(p, COM_MIDDLE) != NULL)	/* Just checking */
 	{
 	    /* Skip middle-comment string */
@@ -6085,7 +6085,7 @@
 
 	/* Don't break until after the comment leader */
 	if (do_comments)
-	    leader_len = get_leader_len(ml_get_curline(), NULL, FALSE);
+	    leader_len = get_leader_len(ml_get_curline(), NULL, FALSE, TRUE);
 	else
 	    leader_len = 0;
 
@@ -6411,7 +6411,7 @@
     /* With the 'c' flag in 'formatoptions' and 't' missing: only format
      * comments. */
     if (has_format_option(FO_WRAP_COMS) && !has_format_option(FO_WRAP)
-				     && get_leader_len(old, NULL, FALSE) == 0)
+				     && get_leader_len(old, NULL, FALSE, TRUE) == 0)
 	return;
 #endif
 
@@ -8565,7 +8565,7 @@
     {
 	temp = curwin->w_cursor.col;
 	if (!can_bs(BS_EOL)		/* only if "eol" included */
-		|| do_join(2, FALSE, TRUE) == FAIL)
+		|| do_join(2, FALSE, TRUE, FALSE) == FAIL)
 	    vim_beep();
 	else
 	    curwin->w_cursor.col = temp;
@@ -8746,7 +8746,7 @@
 			ptr[len - 1] = NUL;
 		}
 
-		(void)do_join(2, FALSE, FALSE);
+		(void)do_join(2, FALSE, FALSE, FALSE);
 		if (temp == NUL && gchar_cursor() != NUL)
 		    inc_cursor();
 	    }
diff --git a/src/ex_docmd.c b/src/ex_docmd.c
index 44b61df..c1640a3 100644
--- a/src/ex_docmd.c
+++ b/src/ex_docmd.c
@@ -8545,7 +8545,7 @@
 	}
 	++eap->line2;
     }
-    (void)do_join(eap->line2 - eap->line1 + 1, !eap->forceit, TRUE);
+    (void)do_join(eap->line2 - eap->line1 + 1, !eap->forceit, TRUE, TRUE);
     beginline(BL_WHITE | BL_FIX);
     ex_may_print(eap);
 }
diff --git a/src/misc1.c b/src/misc1.c
index 8588411..7ba3972 100644
--- a/src/misc1.c
+++ b/src/misc1.c
@@ -671,7 +671,7 @@
 	    ptr = saved_line;
 # ifdef FEAT_COMMENTS
 	    if (flags & OPENLINE_DO_COM)
-		lead_len = get_leader_len(ptr, NULL, FALSE);
+		lead_len = get_leader_len(ptr, NULL, FALSE, TRUE);
 	    else
 		lead_len = 0;
 # endif
@@ -693,7 +693,7 @@
 		}
 # ifdef FEAT_COMMENTS
 		if (flags & OPENLINE_DO_COM)
-		    lead_len = get_leader_len(ptr, NULL, FALSE);
+		    lead_len = get_leader_len(ptr, NULL, FALSE, TRUE);
 		else
 		    lead_len = 0;
 		if (lead_len > 0)
@@ -836,7 +836,7 @@
      */
     end_comment_pending = NUL;
     if (flags & OPENLINE_DO_COM)
-	lead_len = get_leader_len(saved_line, &lead_flags, dir == BACKWARD);
+	lead_len = get_leader_len(saved_line, &lead_flags, dir == BACKWARD, TRUE);
     else
 	lead_len = 0;
     if (lead_len > 0)
@@ -1548,14 +1548,18 @@
  * When "flags" is not NULL, it is set to point to the flags of the recognized
  * comment leader.
  * "backward" must be true for the "O" command.
+ * If "include_space" is set, include trailing whitespace while calculating the
+ * length.
  */
     int
-get_leader_len(line, flags, backward)
+get_leader_len(line, flags, backward, include_space)
     char_u	*line;
     char_u	**flags;
     int		backward;
+    int		include_space;
 {
     int		i, j;
+    int		result;
     int		got_com = FALSE;
     int		found_one;
     char_u	part_buf[COM_MAX_LEN];	/* buffer for one option part */
@@ -1565,7 +1569,7 @@
     char_u	*prev_list;
     char_u	*saved_flags = NULL;
 
-    i = 0;
+    result = i = 0;
     while (vim_iswhite(line[i]))    /* leading white space is ignored */
 	++i;
 
@@ -1668,17 +1672,167 @@
 	if (!found_one)
 	    break;
 
+	result = i;
+
 	/* Include any trailing white space. */
 	while (vim_iswhite(line[i]))
 	    ++i;
 
+	if (include_space)
+	    result = i;
+
 	/* If this comment doesn't nest, stop here. */
 	got_com = TRUE;
 	if (vim_strchr(part_buf, COM_NEST) == NULL)
 	    break;
     }
+    return result;
+}
 
-    return (got_com ? i : 0);
+/*
+ * Return the offset at which the last comment in line starts. If there is no
+ * comment in the whole line, -1 is returned.
+ *
+ * When "flags" is not null, it is set to point to the flags describing the
+ * recognized comment leader.
+ */
+    int
+get_last_leader_offset(line, flags)
+    char_u	*line;
+    char_u	**flags;
+{
+    int		result = -1;
+    int		i, j;
+    int		lower_check_bound = 0;
+    char_u	*string;
+    char_u	*com_leader;
+    char_u	*com_flags;
+    char_u	*list;
+    int		found_one;
+    char_u	part_buf[COM_MAX_LEN];	/* buffer for one option part */
+
+    /*
+     * Repeat to match several nested comment strings.
+     */
+    i = (int)STRLEN(line);
+    while (--i >= lower_check_bound)
+    {
+	/*
+	 * scan through the 'comments' option for a match
+	 */
+	found_one = FALSE;
+	for (list = curbuf->b_p_com; *list; )
+	{
+	    char_u *flags_save = list;
+
+	    /*
+	     * Get one option part into part_buf[].  Advance list to next one.
+	     * put string at start of string.
+	     */
+	    (void)copy_option_part(&list, part_buf, COM_MAX_LEN, ",");
+	    string = vim_strchr(part_buf, ':');
+	    if (string == NULL)	/* If everything is fine, this cannot actually
+				 * happen. */
+	    {
+		continue;
+	    }
+	    *string++ = NUL;	/* Isolate flags from string. */
+	    com_leader = string;
+
+	    /*
+	     * Line contents and string must match.
+	     * When string starts with white space, must have some white space
+	     * (but the amount does not need to match, there might be a mix of
+	     * TABs and spaces).
+	     */
+	    if (vim_iswhite(string[0]))
+	    {
+		if (i == 0 || !vim_iswhite(line[i - 1]))
+		    continue;
+		while (vim_iswhite(string[0]))
+		    ++string;
+	    }
+	    for (j = 0; string[j] != NUL && string[j] == line[i + j]; ++j)
+		/* do nothing */;
+	    if (string[j] != NUL)
+		continue;
+
+	    /*
+	     * When 'b' flag used, there must be white space or an
+	     * end-of-line after the string in the line.
+	     */
+	    if (vim_strchr(part_buf, COM_BLANK) != NULL
+		    && !vim_iswhite(line[i + j]) && line[i + j] != NUL)
+	    {
+		continue;
+	    }
+
+	    /*
+	     * We have found a match, stop searching.
+	     */
+	    found_one = TRUE;
+
+	    if (flags)
+		*flags = flags_save;
+	    com_flags = flags_save;
+
+	    break;
+	}
+
+	if (found_one)
+	{
+	    char_u  part_buf2[COM_MAX_LEN];	/* buffer for one option part */
+	    int     len1, len2, off;
+
+	    result = i;
+	    /*
+	     * If this comment nests, continue searching.
+	     */
+	    if (vim_strchr(part_buf, COM_NEST) != NULL)
+		continue;
+
+	    lower_check_bound = i;
+
+	    /* Let's verify whether the comment leader found is a substring
+	     * of other comment leaders. If it is, let's adjust the
+	     * lower_check_bound so that we make sure that we have determined
+	     * the comment leader correctly.
+	     */
+
+	    while (vim_iswhite(*com_leader))
+		++com_leader;
+	    len1 = (int)STRLEN(com_leader);
+
+	    for (list = curbuf->b_p_com; *list; )
+	    {
+		char_u *flags_save = list;
+
+		(void)copy_option_part(&list, part_buf2, COM_MAX_LEN, ",");
+		if (flags_save == com_flags)
+		    continue;
+		string = vim_strchr(part_buf2, ':');
+		++string;
+		while (vim_iswhite(*string))
+		    ++string;
+		len2 = (int)STRLEN(string);
+		if (len2 == 0)
+		    continue;
+
+		/* Now we have to verify whether string ends with a substring
+		 * beginning the com_leader. */
+		for (off = (len2 > i ? i : len2); off > 0 && off + len1 > len2;)
+		{
+		    --off;
+		    if (!STRNCMP(string + off, com_leader, len2 - off))
+		    {
+			if (i - off < lower_check_bound)
+			    lower_check_bound = i - off;
+		    }
+		}
+	    }
+	}
+    }
+    return result;
 }
 #endif
 
diff --git a/src/normal.c b/src/normal.c
index 3c66a37..6688a9d 100644
--- a/src/normal.c
+++ b/src/normal.c
@@ -1968,7 +1968,7 @@
 		beep_flush();
 	    else
 	    {
-		(void)do_join(oap->line_count, oap->op_type == OP_JOIN, TRUE);
+		(void)do_join(oap->line_count, oap->op_type == OP_JOIN, TRUE, TRUE);
 		auto_format(FALSE, TRUE);
 	    }
 	    break;
@@ -4426,7 +4426,7 @@
 	    break;
 	}
 #ifdef FEAT_COMMENTS
-	if (get_leader_len(ml_get_curline(), NULL, FALSE) > 0)
+	if (get_leader_len(ml_get_curline(), NULL, FALSE, TRUE) > 0)
 	{
 	    /* Ignore this line, continue at start of next line. */
 	    ++curwin->w_cursor.lnum;
@@ -9324,7 +9324,7 @@
 	{
 	    prep_redo(cap->oap->regname, cap->count0,
 			 NUL, cap->cmdchar, NUL, NUL, cap->nchar);
-	    (void)do_join(cap->count0, cap->nchar == NUL, TRUE);
+	    (void)do_join(cap->count0, cap->nchar == NUL, TRUE, TRUE);
 	}
     }
 }
diff --git a/src/ops.c b/src/ops.c
index bc2860a..c1666ac 100644
--- a/src/ops.c
+++ b/src/ops.c
@@ -112,6 +112,9 @@
 # endif
 #endif
 static void	dis_msg __ARGS((char_u *p, int skip_esc));
+#if defined(FEAT_COMMENTS) || defined(PROTO)
+static char_u	*skip_comment __ARGS((char_u *line, int process, int include_space, int *is_comment));
+#endif
 #ifdef FEAT_VISUAL
 static void	block_prep __ARGS((oparg_T *oap, struct block_def *, linenr_T, int));
 #endif
@@ -1987,7 +1990,7 @@
 		curwin->w_cursor = curpos;	/* restore curwin->w_cursor */
 	    }
 	    if (curwin->w_cursor.lnum < curbuf->b_ml.ml_line_count)
-		(void)do_join(2, FALSE, FALSE);
+		(void)do_join(2, FALSE, FALSE, FALSE);
 	}
     }
 
@@ -4197,17 +4200,98 @@
     ui_breakcheck();
 }
 
+#if defined(FEAT_COMMENTS) || defined(PROTO)
+/*
+ * If "process" is TRUE and the line begins with a comment leader (possibly
+ * after some white space), return a pointer to the text after it. Put a boolean
+ * value indicating whether the line ends with an unclosed comment in
+ * "is_comment".
+ * line - line to be processed,
+ * process - if FALSE, will only check whether the line ends with an unclosed
+ *           comment,
+ * include_space - whether to also skip space following the comment leader,
+ * is_comment - will indicate whether the current line ends with an unclosed
+ *              comment.
+ */
+    static char_u *
+skip_comment(line, process, include_space, is_comment)
+    char_u   *line;
+    int      process;
+    int	     include_space;
+    int      *is_comment;
+{
+    char_u *comment_flags = NULL;
+    int    lead_len;
+    int    leader_offset = get_last_leader_offset(line, &comment_flags);
+
+    *is_comment = FALSE;
+    if (leader_offset != -1)
+    {
+	/* Let's check whether the line ends with an unclosed comment.
+	 * If the last comment leader has COM_END in flags, there's no comment.
+	 */
+	while (*comment_flags)
+	{
+	    if (*comment_flags == COM_END
+		    || *comment_flags == ':')
+		break;
+	    ++comment_flags;
+	}
+	if (*comment_flags != COM_END)
+	    *is_comment = TRUE;
+    }
+
+    if (process == FALSE)
+	return line;
+
+    lead_len = get_leader_len(line, &comment_flags, FALSE, include_space);
+
+    if (lead_len == 0)
+	return line;
+
+    /* Find:
+     * - COM_START,
+     * - COM_END,
+     * - colon,
+     * whichever comes first.
+     */
+    while (*comment_flags)
+    {
+	if (*comment_flags == COM_START
+		|| *comment_flags == COM_END
+		|| *comment_flags == ':')
+	{
+	    break;
+	}
+	++comment_flags;
+    }
+
+    /* If we found a colon, it means that we are not processing a line
+     * starting with an opening or a closing part of a three-part
+     * comment. That's good, because we don't want to remove those as
+     * this would be annoying.
+     */
+    if (*comment_flags == ':' || *comment_flags == NUL)
+	line += lead_len;
+
+    return line;
+}
+#endif
+
 /*
  * Join 'count' lines (minimal 2) at cursor position.
  * When "save_undo" is TRUE save lines for undo first.
+ * Set "use_formatoptions" to FALSE when e.g. processing
+ * backspace and comment leaders should not be removed.
  *
  * return FAIL for failure, OK otherwise
  */
     int
-do_join(count, insert_space, save_undo)
+do_join(count, insert_space, save_undo, use_formatoptions)
     long    count;
     int	    insert_space;
     int	    save_undo;
+    int	    use_formatoptions UNUSED;
 {
     char_u	*curr = NULL;
     char_u      *curr_start = NULL;
@@ -4221,6 +4305,13 @@
     linenr_T	t;
     colnr_T	col = 0;
     int		ret = OK;
+#if defined(FEAT_COMMENTS) || defined(PROTO)
+    int		*comments;
+    int		remove_comments = (use_formatoptions == TRUE)
+				  && has_format_option(FO_REMOVE_COMS);
+    int		prev_was_comment;
+#endif
+
 
     if (save_undo && u_save((linenr_T)(curwin->w_cursor.lnum - 1),
 			    (linenr_T)(curwin->w_cursor.lnum + count)) == FAIL)
@@ -4232,6 +4323,17 @@
     spaces = lalloc_clear((long_u)count, TRUE);
     if (spaces == NULL)
 	return FAIL;
+#if defined(FEAT_COMMENTS) || defined(PROTO)
+    if (remove_comments)
+    {
+	comments = (int *)lalloc_clear((long_u)count * sizeof(int), TRUE);
+	if (comments == NULL)
+	{
+	    vim_free(spaces);
+	    return FAIL;
+	}
+    }
+#endif
 
     /*
      * Don't move anything, just compute the final line length
@@ -4240,6 +4342,25 @@
     for (t = 0; t < count; ++t)
     {
 	curr = curr_start = ml_get((linenr_T)(curwin->w_cursor.lnum + t));
+#if defined(FEAT_COMMENTS) || defined(PROTO)
+	if (remove_comments)
+	{
+	    /* We don't want to remove the comment leader if the
+	     * previous line is not a comment. */
+	    if (t > 0 && prev_was_comment)
+	    {
+
+		char_u *new_curr = skip_comment(curr, TRUE, insert_space,
+							   &prev_was_comment);
+		comments[t] = new_curr - curr;
+		curr = new_curr;
+	    }
+	    else
+		curr = skip_comment(curr, FALSE, insert_space,
+							   &prev_was_comment);
+	}
+#endif
+
 	if (insert_space && t > 0)
 	{
 	    curr = skipwhite(curr);
@@ -4327,6 +4448,10 @@
 	if (t == 0)
 	    break;
 	curr = curr_start = ml_get((linenr_T)(curwin->w_cursor.lnum + t - 1));
+#if defined(FEAT_COMMENTS) || defined(PROTO)
+	if (remove_comments)
+	    curr += comments[t - 1];
+#endif
 	if (insert_space && t > 1)
 	    curr = skipwhite(curr);
 	currsize = (int)STRLEN(curr);
@@ -4364,6 +4489,10 @@
 
 theend:
     vim_free(spaces);
+#if defined(FEAT_COMMENTS) || defined(PROTO)
+    if (remove_comments)
+	vim_free(comments);
+#endif
     return ret;
 }
 
@@ -4788,7 +4917,7 @@
 						      (long)-next_leader_len);
 #endif
 		curwin->w_cursor.lnum--;
-		if (do_join(2, TRUE, FALSE) == FAIL)
+		if (do_join(2, TRUE, FALSE, FALSE) == FAIL)
 		{
 		    beep_flush();
 		    break;
@@ -4844,7 +4973,7 @@
 
     ptr = ml_get(lnum);
     if (do_comments)
-	*leader_len = get_leader_len(ptr, leader_flags, FALSE);
+	*leader_len = get_leader_len(ptr, leader_flags, FALSE, TRUE);
     else
 	*leader_len = 0;
 
diff --git a/src/option.h b/src/option.h
index 9dd9387..756cd1a 100644
--- a/src/option.h
+++ b/src/option.h
@@ -104,10 +104,11 @@
 #define FO_ONE_LETTER	'1'
 #define FO_WHITE_PAR	'w'	/* trailing white space continues paragr. */
 #define FO_AUTO		'a'	/* automatic formatting */
+#define FO_REMOVE_COMS	'j'	/* remove comment leaders when joining lines */
 
 #define DFLT_FO_VI	"vt"
 #define DFLT_FO_VIM	"tcq"
-#define FO_ALL		"tcroq2vlb1mMBn,aw"	/* for do_set() */
+#define FO_ALL		"tcroq2vlb1mMBn,awj"	/* for do_set() */
 
 /* characters for the p_cpo option: */
 #define CPO_ALTREAD	'a'	/* ":read" sets alternate file name */
diff --git a/src/proto/misc1.pro b/src/proto/misc1.pro
index 93bfff6..f646a1c 100644
--- a/src/proto/misc1.pro
+++ b/src/proto/misc1.pro
@@ -6,7 +6,8 @@
 int set_indent __ARGS((int size, int flags));
 int get_number_indent __ARGS((linenr_T lnum));
 int open_line __ARGS((int dir, int flags, int old_indent));
-int get_leader_len __ARGS((char_u *line, char_u **flags, int backward));
+int get_leader_len __ARGS((char_u *line, char_u **flags, int backward, int do_skip_space));
+int get_last_leader_offset __ARGS((char_u *line, char_u **flags));
 int plines __ARGS((linenr_T lnum));
 int plines_win __ARGS((win_T *wp, linenr_T lnum, int winheight));
 int plines_nofill __ARGS((linenr_T lnum));
diff --git a/src/proto/ops.pro b/src/proto/ops.pro
index d07c260..85fb983 100644
--- a/src/proto/ops.pro
+++ b/src/proto/ops.pro
@@ -36,7 +36,7 @@
 int preprocs_left __ARGS((void));
 int get_register_name __ARGS((int num));
 void ex_display __ARGS((exarg_T *eap));
-int do_join __ARGS((long count, int insert_space, int save_undo));
+int do_join __ARGS((long count, int insert_space, int save_undo, int use_formatoptions));
 void op_format __ARGS((oparg_T *oap, int keep_cursor));
 void op_formatexpr __ARGS((oparg_T *oap));
 int fex_format __ARGS((linenr_T lnum, long count, int c));
diff --git a/src/search.c b/src/search.c
index 59de988..1db967d 100644
--- a/src/search.c
+++ b/src/search.c
@@ -1548,7 +1548,7 @@
     int			len;
     int			stop = TRUE;
 #ifdef FEAT_MBYTE
-    static char_u	bytes[MB_MAXBYTES];
+    static char_u	bytes[MB_MAXBYTES + 1];
     static int		bytelen = 1;	/* >1 for multi-byte char */
 #endif
 
@@ -4901,7 +4901,7 @@
 #ifdef FEAT_COMMENTS
 			if ((*line != '#' ||
 				STRNCMP(skipwhite(line + 1), "define", 6) != 0)
-				&& get_leader_len(line, NULL, FALSE))
+				&& get_leader_len(line, NULL, FALSE, TRUE))
 			    matched = FALSE;
 
 			/*
diff --git a/src/testdir/test29.in b/src/testdir/test29.in
index 6c7d3d5..cf24642 100644
--- a/src/testdir/test29.in
+++ b/src/testdir/test29.in
Binary files differ
diff --git a/src/testdir/test29.ok b/src/testdir/test29.ok
index 97abf08..a5546ab 100644
--- a/src/testdir/test29.ok
+++ b/src/testdir/test29.ok
@@ -47,3 +47,40 @@
 asdfasdf 	asdf
 asdfasdf		asdf
 zx cvn.  as dfg? hjkl iop! ert  a
+
+
+{
+/* Make sure the previous comment leader is not removed. */
+/* Make sure the previous comment leader is not removed. */
+// Should the next comment leader be left alone? Yes.
+// Should the next comment leader be left alone? Yes.
+/* Here the comment leader should be left intact. */ // And so should this one.
+/* Here the comment leader should be left intact. */ // And so should this one.
+if (condition) // Remove the next comment leader! OK, I will.
+    action();
+if (condition) // Remove the next comment leader! OK, I will.
+    action();
+}
+
+
+{
+/* Make sure the previous comment leader is not removed.  */
+/* Make sure the previous comment leader is not removed.  */
+// Should the next comment leader be left alone?  Yes.
+// Should the next comment leader be left alone?  Yes.
+/* Here the comment leader should be left intact. */ // And so should this one.
+/* Here the comment leader should be left intact. */ // And so should this one.
+if (condition) // Remove the next comment leader!  OK, I will.
+    action();
+if (condition) // Remove the next comment leader!  OK, I will.
+    action();
+int i = 7 /* foo *// 3 // comment
+ ;
+int i = 7 /* foo *// 3 // comment
+ ;
+># Note that the last character of the ending comment leader (left angle bracket) is a comment leader itself. Make sure that this comment leader is not removed from the next line #< < On this line a new comment is opened which spans 2 lines. This comment should retain its comment leader.
+># Note that the last character of the ending comment leader (left angle bracket) is a comment leader itself. Make sure that this comment leader is not removed from the next line #< < On this line a new comment is opened which spans 2 lines. This comment should retain its comment leader.
+
+Some code!// Make sure backspacing does not remove this comment leader.
+}
+
diff --git a/src/version.c b/src/version.c
index a6b23f1..a7e5445 100644
--- a/src/version.c
+++ b/src/version.c
@@ -715,6 +715,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    541,
+/**/
     540,
 /**/
     539,