diff --git a/src/evalfunc.c b/src/evalfunc.c
index 2979611..37cb72f 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -664,6 +664,7 @@
     {"map",		2, 2, FEARG_1,	  ret_any,	f_map},
     {"maparg",		1, 4, FEARG_1,	  ret_string,	f_maparg},
     {"mapcheck",	1, 3, FEARG_1,	  ret_string,	f_mapcheck},
+    {"mapset",		3, 3, FEARG_1,	  ret_void,	f_mapset},
     {"match",		2, 4, FEARG_1,	  ret_any,	f_match},
     {"matchadd",	2, 5, FEARG_1,	  ret_number,	f_matchadd},
     {"matchaddpos",	2, 5, FEARG_1,	  ret_number,	f_matchaddpos},
diff --git a/src/map.c b/src/map.c
index 2e20d40..34a956e 100644
--- a/src/map.c
+++ b/src/map.c
@@ -204,6 +204,86 @@
     out_flush();			// show one line at a time
 }
 
+    static int
+map_add(
+	mapblock_T  **map_table,
+	mapblock_T  **abbr_table,
+	char_u	    *keys,
+	char_u	    *rhs,
+	char_u	    *orig_rhs,
+	int	    expr,
+	int	    noremap,
+	int	    nowait,
+	int	    silent,
+	int	    mode,
+	int	    is_abbr,
+#ifdef FEAT_EVAL
+	scid_T	    sid,	    // -1 to use current_sctx
+	linenr_T    lnum,
+#endif
+	int	    simplified)
+{
+    mapblock_T	*mp = ALLOC_ONE(mapblock_T);
+
+    if (mp == NULL)
+	return FAIL;
+
+    // If CTRL-C has been mapped, don't always use it for Interrupting.
+    if (*keys == Ctrl_C)
+    {
+	if (map_table == curbuf->b_maphash)
+	    curbuf->b_mapped_ctrl_c |= mode;
+	else
+	    mapped_ctrl_c |= mode;
+    }
+
+    mp->m_keys = vim_strsave(keys);
+    mp->m_str = vim_strsave(rhs);
+    mp->m_orig_str = vim_strsave(orig_rhs);
+    if (mp->m_keys == NULL || mp->m_str == NULL)
+    {
+	vim_free(mp->m_keys);
+	vim_free(mp->m_str);
+	vim_free(mp->m_orig_str);
+	vim_free(mp);
+	return FAIL;
+    }
+    mp->m_keylen = (int)STRLEN(mp->m_keys);
+    mp->m_noremap = noremap;
+    mp->m_nowait = nowait;
+    mp->m_silent = silent;
+    mp->m_mode = mode;
+    mp->m_simplified = simplified;
+#ifdef FEAT_EVAL
+    mp->m_expr = expr;
+    if (sid >= 0)
+    {
+	mp->m_script_ctx.sc_sid = sid;
+	mp->m_script_ctx.sc_lnum = lnum;
+    }
+    else
+    {
+	mp->m_script_ctx = current_sctx;
+	mp->m_script_ctx.sc_lnum += SOURCING_LNUM;
+    }
+#endif
+
+    // add the new entry in front of the abbrlist or maphash[] list
+    if (is_abbr)
+    {
+	mp->m_next = *abbr_table;
+	*abbr_table = mp;
+    }
+    else
+    {
+	int n = MAP_HASH(mp->m_mode, mp->m_keys[0]);
+
+	mp->m_next = map_table[n];
+	map_table[n] = mp;
+    }
+    return OK;
+}
+
 /*
  * map[!]		    : show all key mappings
  * map[!] {lhs}		    : show key mapping for {lhs}
@@ -501,7 +581,8 @@
 	    msg_start();
 
 	// Check if a new local mapping wasn't already defined globally.
-	if (map_table == curbuf->b_maphash && haskey && hasarg && maptype != 1)
+	if (unique && map_table == curbuf->b_maphash
+					   && haskey && hasarg && maptype != 1)
 	{
 	    // need to loop over all global hash lists
 	    for (hash = 0; hash < 256 && !got_int; ++hash)
@@ -519,7 +600,6 @@
 		    // check entries with the same mode
 		    if ((mp->m_mode & mode) != 0
 			    && mp->m_keylen == len
-			    && unique
 			    && STRNCMP(mp->m_keys, keys, (size_t)len) == 0)
 		    {
 			if (abbrev)
@@ -759,58 +839,17 @@
 	    continue;	// have added the new entry already
 
 	// Get here when adding a new entry to the maphash[] list or abbrlist.
-	mp = ALLOC_ONE(mapblock_T);
-	if (mp == NULL)
+	if (map_add(map_table, abbr_table, keys, rhs, orig_rhs, expr,
+		    noremap, nowait, silent, mode,
+		    abbrev,
+#ifdef FEAT_EVAL
+		    /* sid */ -1, /* lnum */ 0,
+#endif
+		    did_simplify && keyround == 1) == FAIL)
 	{
 	    retval = 4;	    // no mem
 	    goto theend;
 	}
-
-	// If CTRL-C has been mapped, don't always use it for Interrupting.
-	if (*keys == Ctrl_C)
-	{
-	    if (map_table == curbuf->b_maphash)
-		curbuf->b_mapped_ctrl_c |= mode;
-	    else
-		mapped_ctrl_c |= mode;
-	}
-
-	mp->m_keys = vim_strsave(keys);
-	mp->m_str = vim_strsave(rhs);
-	mp->m_orig_str = vim_strsave(orig_rhs);
-	if (mp->m_keys == NULL || mp->m_str == NULL)
-	{
-	    vim_free(mp->m_keys);
-	    vim_free(mp->m_str);
-	    vim_free(mp->m_orig_str);
-	    vim_free(mp);
-	    retval = 4;	// no mem
-	    goto theend;
-	}
-	mp->m_keylen = (int)STRLEN(mp->m_keys);
-	mp->m_noremap = noremap;
-	mp->m_nowait = nowait;
-	mp->m_silent = silent;
-	mp->m_mode = mode;
-	mp->m_simplified = did_simplify && keyround == 1;
-#ifdef FEAT_EVAL
-	mp->m_expr = expr;
-	mp->m_script_ctx = current_sctx;
-	mp->m_script_ctx.sc_lnum += SOURCING_LNUM;
-#endif
-
-	// add the new entry in front of the abbrlist or maphash[] list
-	if (abbrev)
-	{
-	    mp->m_next = *abbr_table;
-	    *abbr_table = mp;
-	}
-	else
-	{
-	    n = MAP_HASH(mp->m_mode, mp->m_keys[0]);
-	    mp->m_next = map_table[n];
-	    map_table[n] = mp;
-	}
     }
 
 theend:
@@ -2209,13 +2248,96 @@
 	dict_add_number(dict, "buffer", (long)buffer_local);
 	dict_add_number(dict, "nowait", mp->m_nowait ? 1L : 0L);
 	dict_add_string(dict, "mode", mapmode);
+	dict_add_number(dict, "simplified", mp->m_simplified);
 
 	vim_free(lhs);
 	vim_free(mapmode);
     }
 }
+
+/*
+ * "mapset()" function
+ */
+    void
+f_mapset(typval_T *argvars, typval_T *rettv UNUSED)
+{
+    char_u	*keys;
+    char_u	*keys_buf = NULL;
+    char_u	*which;
+    int		mode;
+    char_u	buf[NUMBUFLEN];
+    int		is_abbr;
+    dict_T	*d;
+    char_u	*lhs;
+    char_u	*rhs;
+    int		noremap;
+    int		expr;
+    int		silent;
+    scid_T	sid;
+    linenr_T	lnum;
+    mapblock_T	**map_table = maphash;
+    mapblock_T  **abbr_table = &first_abbr;
+    int		nowait;
+    int		simplified;
+    char_u	*arg;
+
+    which = tv_get_string_buf_chk(&argvars[0], buf);
+    mode = get_map_mode(&which, 0);
+    is_abbr = (int)tv_get_number(&argvars[1]);
+
+    if (argvars[2].v_type != VAR_DICT)
+    {
+	emsg(_(e_dictkey));
+	return;
+    }
+    d = argvars[2].vval.v_dict;
+
+    // Get the values in the same order as above in get_maparg().
+    lhs = dict_get_string(d, (char_u *)"lhs", FALSE);
+    if (lhs == NULL)
+    {
+	emsg(_("E99: lhs entry missing in mapset() dict argument"));
+	return;
+    }
+    rhs = dict_get_string(d, (char_u *)"rhs", FALSE);
+    if (rhs == NULL)
+    {
+	emsg(_("E99: rhs entry missing in mapset() dict argument"));
+	return;
+    }
+
+    noremap = dict_get_number(d, (char_u *)"noremap") ? REMAP_NONE: 0;
+    if (dict_get_number(d, (char_u *)"script") != 0)
+	noremap = REMAP_SCRIPT;
+    expr = dict_get_number(d, (char_u *)"expr") != 0;
+    silent = dict_get_number(d, (char_u *)"silent") != 0;
+    sid = dict_get_number(d, (char_u *)"sid");
+    lnum = dict_get_number(d, (char_u *)"lnum");
+    if (dict_get_number(d, (char_u *)"buffer"))
+    {
+	map_table = curbuf->b_maphash;
+	abbr_table = &curbuf->b_first_abbr;
+    }
+    nowait = dict_get_number(d, (char_u *)"nowait") != 0;
+    // mode from the dict is not used
+    simplified = dict_get_number(d, (char_u *)"simplified") != 0;
+
+    // Delete any existing mapping for this lhs and mode.
+    arg = vim_strsave(lhs);
+    if (arg == NULL)
+	return;
+    do_map(1, arg, mode, is_abbr);
+    vim_free(arg);
+
+    keys = replace_termcodes(lhs, &keys_buf,
+				      REPTERM_FROM_PART | REPTERM_DO_LT, NULL);
+    (void)map_add(map_table, abbr_table, keys, rhs, rhs, expr,
+		noremap, nowait, silent, mode, is_abbr, sid, lnum, simplified);
+    vim_free(keys_buf);
+}
 #endif
 
+
 #if defined(MSWIN) || defined(MACOS_X)
 
 # define VIS_SEL	(VISUAL+SELECTMODE)	// abbreviation
diff --git a/src/proto/map.pro b/src/proto/map.pro
index cf1b31a..6da455a 100644
--- a/src/proto/map.pro
+++ b/src/proto/map.pro
@@ -18,6 +18,7 @@
 void check_map_keycodes(void);
 char_u *check_map(char_u *keys, int mode, int exact, int ign_mod, int abbr, mapblock_T **mp_ptr, int *local_ptr);
 void get_maparg(typval_T *argvars, typval_T *rettv, int exact);
+void f_mapset(typval_T *argvars, typval_T *rettv);
 void init_mappings(void);
 void add_map(char_u *map, int mode);
 int langmap_adjust_mb(int c);
diff --git a/src/testdir/test_maparg.vim b/src/testdir/test_maparg.vim
index cc72e7e..5fb8045 100644
--- a/src/testdir/test_maparg.vim
+++ b/src/testdir/test_maparg.vim
@@ -1,12 +1,12 @@
-" Tests for maparg().
+" Tests for maparg(), mapcheck() and mapset().
 " Also test utf8 map with a 0x80 byte.
 " Also test mapcheck()
 
-function s:SID()     
+func s:SID()     
   return str2nr(matchstr(expand('<sfile>'), '<SNR>\zs\d\+\ze_SID$'))
-endfun
+endfunc
 
-function Test_maparg()
+funct Test_maparg()
   new
   set cpo-=<
   set encoding=utf8
@@ -18,23 +18,23 @@
   call assert_equal("is<F4>foo", maparg('foo<C-V>'))
   call assert_equal({'silent': 0, 'noremap': 0, 'script': 0, 'lhs': 'foo<C-V>',
         \ 'mode': ' ', 'nowait': 0, 'expr': 0, 'sid': sid, 'lnum': lnum + 1, 
-	\ 'rhs': 'is<F4>foo', 'buffer': 0},
+	\ 'simplified': 1, 'rhs': 'is<F4>foo', 'buffer': 0},
 	\ maparg('foo<C-V>', '', 0, 1))
   call assert_equal({'silent': 1, 'noremap': 1, 'script': 1, 'lhs': 'bar', 'mode': 'v',
         \ 'nowait': 0, 'expr': 1, 'sid': sid, 'lnum': lnum + 2,
-	\ 'rhs': 'isbar', 'buffer': 1},
+	\ 'simplified': 0, 'rhs': 'isbar', 'buffer': 1},
         \ 'bar'->maparg('', 0, 1))
   let lnum = expand('<sflnum>')
   map <buffer> <nowait> foo bar
   call assert_equal({'silent': 0, 'noremap': 0, 'script': 0, 'lhs': 'foo', 'mode': ' ',
         \ 'nowait': 1, 'expr': 0, 'sid': sid, 'lnum': lnum + 1, 'rhs': 'bar',
-	\ 'buffer': 1},
+	\ 'simplified': 0, 'buffer': 1},
         \ maparg('foo', '', 0, 1))
   let lnum = expand('<sflnum>')
   tmap baz foo
   call assert_equal({'silent': 0, 'noremap': 0, 'script': 0, 'lhs': 'baz', 'mode': 't',
         \ 'nowait': 0, 'expr': 0, 'sid': sid, 'lnum': lnum + 1, 'rhs': 'foo',
-	\ 'buffer': 0},
+	\ 'simplified': 0, 'buffer': 0},
         \ maparg('baz', 't', 0, 1))
 
   map abc x<char-114>x
@@ -75,7 +75,7 @@
   let d = maparg('esc', 'i', 1, 1)
   call assert_equal(['esc', "\<C-V>\<C-V>\<Esc>", '!'], [d.lhs, d.rhs, d.mode])
   abclear
-endfunction
+endfunc
 
 func Test_mapcheck()
   call assert_equal('', mapcheck('a'))
@@ -116,7 +116,7 @@
   unabbr ab
 endfunc
 
-function Test_range_map()
+func Test_range_map()
   new
   " Outside of the range, minimum
   inoremap <Char-0x1040> a
@@ -131,6 +131,31 @@
   inoremap <Char-0xf040> d
   execute "normal a\uf040\<Esc>"
   call assert_equal("abcd", getline(1))
-endfunction
+endfunc
+
+func One_mapset_test(keys)
+  exe 'nnoremap ' .. a:keys .. ' original<CR>'
+  let orig = maparg(a:keys, 'n', 0, 1)
+  call assert_equal(a:keys, orig.lhs)
+  call assert_equal('original<CR>', orig.rhs)
+  call assert_equal('n', orig.mode)
+
+  exe 'nunmap ' .. a:keys
+  let d = maparg(a:keys, 'n', 0, 1)
+  call assert_equal({}, d)
+
+  call mapset('n', 0, orig)
+  let d = maparg(a:keys, 'n', 0, 1)
+  call assert_equal(a:keys, d.lhs)
+  call assert_equal('original<CR>', d.rhs)
+  call assert_equal('n', d.mode)
+
+  exe 'nunmap ' .. a:keys
+endfunc
+
+func Test_mapset()
+  call One_mapset_test('K')
+  call One_mapset_test('<F3>')
+endfunc
 
 " vim: shiftwidth=2 sts=2 expandtab
diff --git a/src/version.c b/src/version.c
index d36fa4a..565ebbb 100644
--- a/src/version.c
+++ b/src/version.c
@@ -747,6 +747,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    807,
+/**/
     806,
 /**/
     805,