diff --git a/src/charset.c b/src/charset.c
index 470698f..4dcde14 100644
--- a/src/charset.c
+++ b/src/charset.c
@@ -2089,6 +2089,17 @@
 }
 
 /*
+ * skiptowhite: skip over text until ' ' or '\t' or newline or NUL.
+ */
+    char_u *
+skiptowhite_or_nl(char_u *p)
+{
+    while (*p != ' ' && *p != '\t' && *p != NL && *p != NUL)
+	++p;
+    return p;
+}
+
+/*
  * skiptowhite_esc: Like skiptowhite(), but also skip escaped chars
  */
     char_u *
diff --git a/src/evalvars.c b/src/evalvars.c
index f16d475..62728ed 100644
--- a/src/evalvars.c
+++ b/src/evalvars.c
@@ -779,8 +779,10 @@
     int		eval_failed = FALSE;
     cctx_T	*cctx = vim9compile ? eap->cookie : NULL;
     int		count = 0;
+    int		heredoc_in_string = FALSE;
+    char_u	*line_arg = NULL;
 
-    if (eap->ea_getline == NULL)
+    if (eap->ea_getline == NULL && vim_strchr(cmd, '\n') == NULL)
     {
 	emsg(_(e_cannot_use_heredoc_here));
 	return NULL;
@@ -824,8 +826,14 @@
     if (*cmd != NUL && *cmd != comment_char)
     {
 	marker = skipwhite(cmd);
-	p = skiptowhite(marker);
-	if (*skipwhite(p) != NUL && *skipwhite(p) != comment_char)
+	p = skiptowhite_or_nl(marker);
+	if (*p == NL)
+	{
+	    // heredoc in a string
+	    line_arg = p + 1;
+	    heredoc_in_string = TRUE;
+	}
+	else if (*skipwhite(p) != NUL && *skipwhite(p) != comment_char)
 	{
 	    semsg(_(e_trailing_characters_str), p);
 	    return NULL;
@@ -859,12 +867,38 @@
 	int	mi = 0;
 	int	ti = 0;
 
-	vim_free(theline);
-	theline = eap->ea_getline(NUL, eap->cookie, 0, FALSE);
-	if (theline == NULL)
+	if (heredoc_in_string)
 	{
-	    semsg(_(e_missing_end_marker_str), marker);
-	    break;
+	    char_u	*next_line;
+
+	    // heredoc in a string separated by newlines.  Get the next line
+	    // from the string.
+
+	    if (*line_arg == NUL)
+	    {
+		semsg(_(e_missing_end_marker_str), marker);
+		break;
+	    }
+
+	    theline = line_arg;
+	    next_line = vim_strchr(theline, '\n');
+	    if (next_line == NULL)
+		line_arg += STRLEN(line_arg);
+	    else
+	    {
+		*next_line = NUL;
+		line_arg = next_line + 1;
+	    }
+	}
+	else
+	{
+	    vim_free(theline);
+	    theline = eap->ea_getline(NUL, eap->cookie, 0, FALSE);
+	    if (theline == NULL)
+	    {
+		semsg(_(e_missing_end_marker_str), marker);
+		break;
+	    }
 	}
 
 	// with "trim": skip the indent matching the :let line to find the
@@ -911,6 +945,8 @@
 	}
 	else
 	{
+	    int	    free_str = FALSE;
+
 	    if (evalstr && !eap->skip)
 	    {
 		str = eval_all_expr_in_str(str);
@@ -920,15 +956,20 @@
 		    eval_failed = TRUE;
 		    continue;
 		}
-		vim_free(theline);
-		theline = str;
+		free_str = TRUE;
 	    }
 
 	    if (list_append_string(l, str, -1) == FAIL)
 		break;
+	    if (free_str)
+		vim_free(str);
 	}
     }
-    vim_free(theline);
+    if (heredoc_in_string)
+	// Next command follows the heredoc in the string.
+	eap->nextcmd = line_arg;
+    else
+	vim_free(theline);
     vim_free(text_indent);
 
     if (vim9compile && cctx->ctx_skip != SKIP_YES && !eval_failed)
diff --git a/src/proto/charset.pro b/src/proto/charset.pro
index a747319..a4f6c45 100644
--- a/src/proto/charset.pro
+++ b/src/proto/charset.pro
@@ -61,6 +61,7 @@
 int vim_toupper(int c);
 int vim_tolower(int c);
 char_u *skiptowhite(char_u *p);
+char_u *skiptowhite_or_nl(char_u *p);
 char_u *skiptowhite_esc(char_u *p);
 long getdigits(char_u **pp);
 long getdigits_quoted(char_u **pp);
diff --git a/src/testdir/test_let.vim b/src/testdir/test_let.vim
index 5ee2e9b..e6d9cae 100644
--- a/src/testdir/test_let.vim
+++ b/src/testdir/test_let.vim
@@ -715,6 +715,20 @@
   LINES
   call v9.CheckScriptFailure(lines, 'E15:')
 
+  " Test for using heredoc in a single string using execute()
+  call assert_equal(["['one', 'two']"],
+    \ execute("let x =<< trim END\n  one\n  two\nEND\necho x")->split("\n"))
+  call assert_equal(["['  one', '  two']"],
+    \ execute("let x =<< END\n  one\n  two\nEND\necho x")->split("\n"))
+  let cmd = 'execute("let x =<< END\n  one\n  two\necho x")'
+  call assert_fails(cmd, "E990: Missing end marker 'END'")
+  let cmd = 'execute("let x =<<\n  one\n  two\necho x")'
+  call assert_fails(cmd, "E990: Missing end marker ''")
+  let cmd = 'execute("let x =<< trim\n  one\n  two\necho x")'
+  call assert_fails(cmd, "E221: Marker cannot start with lower case letter")
+  let cmd = 'execute("let x =<< eval END\n  one\n  two{y}\nEND\necho x")'
+  call assert_fails(cmd, 'E121: Undefined variable: y')
+
   " skipped heredoc
   if 0
     let msg =<< trim eval END
diff --git a/src/testdir/test_vim9_script.vim b/src/testdir/test_vim9_script.vim
index cd693e5..136c81d 100644
--- a/src/testdir/test_vim9_script.vim
+++ b/src/testdir/test_vim9_script.vim
@@ -458,7 +458,7 @@
   SomeCommand
 endfunc
 
-def Test_autocommand_block()
+def Test_command_block()
   com SomeCommand {
       g:someVar = 'some'
     }
@@ -469,7 +469,105 @@
   unlet g:someVar
 enddef
 
-def Test_command_block()
+" Test for using heredoc in a :command command block
+def Test_command_block_heredoc()
+  var lines =<< trim CODE
+    vim9script
+    com SomeCommand {
+        g:someVar =<< trim END
+          aaa
+          bbb
+        END
+      }
+    SomeCommand
+    assert_equal(['aaa', 'bbb'], g:someVar)
+    def Foo()
+      g:someVar = []
+      SomeCommand
+      assert_equal(['aaa', 'bbb'], g:someVar)
+    enddef
+    Foo()
+    delcommand SomeCommand
+    unlet g:someVar
+  CODE
+  v9.CheckSourceSuccess( lines)
+
+  # Execute a command with heredoc in a block
+  lines =<< trim CODE
+    vim9script
+    com SomeCommand {
+        g:someVar =<< trim END
+          aaa
+          bbb
+        END
+      }
+    execute('SomeCommand')
+    assert_equal(['aaa', 'bbb'], g:someVar)
+    delcommand SomeCommand
+    unlet g:someVar
+  CODE
+  v9.CheckSourceSuccess(lines)
+
+  # heredoc evaluation
+  lines =<< trim CODE
+    vim9script
+    com SomeCommand {
+        var suffix = '---'
+        g:someVar =<< trim eval END
+          ccc{suffix}
+          ddd
+        END
+      }
+    SomeCommand
+    assert_equal(['ccc---', 'ddd'], g:someVar)
+    def Foo()
+      g:someVar = []
+      SomeCommand
+      assert_equal(['ccc---', 'ddd'], g:someVar)
+    enddef
+    Foo()
+    delcommand SomeCommand
+    unlet g:someVar
+  CODE
+  v9.CheckSourceSuccess(lines)
+
+  # command following heredoc
+  lines =<< trim CODE
+    vim9script
+    com SomeCommand {
+        var l =<< trim END
+          eee
+          fff
+        END
+        g:someVar = l
+      }
+    SomeCommand
+    assert_equal(['eee', 'fff'], g:someVar)
+    delcommand SomeCommand
+    unlet g:someVar
+  CODE
+  v9.CheckSourceSuccess(lines)
+
+  # Error in heredoc
+  lines =<< trim CODE
+    vim9script
+    com SomeCommand {
+        g:someVar =<< trim END
+          eee
+          fff
+      }
+    try
+      SomeCommand
+    catch
+      assert_match("E990: Missing end marker 'END'", v:exception)
+    endtry
+    delcommand SomeCommand
+    unlet g:someVar
+  CODE
+  v9.CheckSourceSuccess(lines)
+enddef
+
+def Test_autocommand_block()
   au BufNew *.xml {
       g:otherVar = 'other'
     }
diff --git a/src/version.c b/src/version.c
index f2d28ce..1a924e7 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    312,
+/**/
     311,
 /**/
     310,