diff --git a/tools/cli/command.go b/tools/cli/command.go
index d19815ee9..5527865b1 100644
--- a/tools/cli/command.go
+++ b/tools/cli/command.go
@@ -347,6 +347,30 @@ func (self *Command) Add(s OptionSpec) *Option {
 	return self.AddToGroup("", s)
 }
 
+func (self *Command) FindOptions(name_with_hyphens string) []*Option {
+	ans := make([]*Option, 0, 4)
+	for _, g := range self.OptionGroups {
+		x := g.FindOptions(name_with_hyphens)
+		if x != nil {
+			ans = append(ans, x...)
+		}
+	}
+	depth := 0
+	for p := self.Parent; p != nil; p = p.Parent {
+		depth++
+		x := p.FindOptions(name_with_hyphens)
+		if x != nil {
+			for _, po := range x {
+				if po.Depth >= depth {
+					ans = append(ans, po)
+				}
+			}
+		}
+	}
+	return ans
+
+}
+
 func (self *Command) FindOption(name_with_hyphens string) *Option {
 	for _, g := range self.OptionGroups {
 		q := g.FindOption(name_with_hyphens)
diff --git a/tools/cli/group.go b/tools/cli/group.go
index 040766635..e69ec35f6 100644
--- a/tools/cli/group.go
+++ b/tools/cli/group.go
@@ -82,6 +82,19 @@ func (self *OptionGroup) AddOptionFromString(parent *Command, items ...string) (
 	return ans, err
 }
 
+func (self *OptionGroup) FindOptions(prefix_with_hyphens string) []*Option {
+	is_short := !strings.HasPrefix(prefix_with_hyphens, "--")
+	option_name := NormalizeOptionName(prefix_with_hyphens)
+	ans := make([]*Option, 0, 4)
+	for _, q := range self.Options {
+		if q.MatchingAlias(option_name, is_short) != "" {
+			ans = append(ans, q)
+		}
+	}
+	return ans
+
+}
+
 func (self *OptionGroup) FindOption(name_with_hyphens string) *Option {
 	is_short := !strings.HasPrefix(name_with_hyphens, "--")
 	option_name := NormalizeOptionName(name_with_hyphens)
diff --git a/tools/cli/option.go b/tools/cli/option.go
index 75da94707..d30b45d97 100644
--- a/tools/cli/option.go
+++ b/tools/cli/option.go
@@ -75,6 +75,15 @@ func (self *Option) needs_argument() bool {
 	return self.OptionType != BoolOption && self.OptionType != CountOption
 }
 
+func (self *Option) MatchingAlias(prefix_without_hyphens string, is_short bool) string {
+	for _, a := range self.Aliases {
+		if a.IsShort == is_short && strings.HasPrefix(a.NameWithoutHyphens, prefix_without_hyphens) {
+			return a.String()
+		}
+	}
+	return ""
+}
+
 func (self *Option) HasAlias(name_without_hyphens string, is_short bool) bool {
 	for _, a := range self.Aliases {
 		if a.IsShort == is_short && a.NameWithoutHyphens == name_without_hyphens {
diff --git a/tools/cli/parse-args.go b/tools/cli/parse-args.go
index 04e3aa131..1706a3000 100644
--- a/tools/cli/parse-args.go
+++ b/tools/cli/parse-args.go
@@ -20,9 +20,19 @@ func (self *Command) parse_args(ctx *Context, args []string) error {
 	consume_arg := func() string { ans := args_to_parse[0]; args_to_parse = args_to_parse[1:]; return ans }
 
 	handle_option := func(opt_str string, has_val bool, opt_val string, val_not_allowed bool) error {
-		opt := self.FindOption(opt_str)
-		if opt == nil {
+		possible_options := self.FindOptions(opt_str)
+		var opt *Option
+		if len(possible_options) == 1 {
+			opt = possible_options[0]
+			opt_str = opt.MatchingAlias(NormalizeOptionName(opt_str), !strings.HasPrefix(opt_str, "--"))
+		} else if len(possible_options) == 0 {
 			return &ParseError{Message: fmt.Sprintf("Unknown option: :yellow:`%s`", opt_str)}
+		} else {
+			ambi := make([]string, len(possible_options))
+			for i, o := range possible_options {
+				ambi[i] = o.MatchingAlias(NormalizeOptionName(opt_str), !strings.HasPrefix(opt_str, "--"))
+			}
+			return &ParseError{Message: fmt.Sprintf("Ambiguous option: :yellow:`%s` could be any of: %s", opt_str, strings.Join(ambi, ", "))}
 		}
 		opt.seen_option = opt_str
 		needs_arg := opt.needs_argument()
diff --git a/tools/cli/types_test.go b/tools/cli/types_test.go
index 415640528..4309502ae 100644
--- a/tools/cli/types_test.go
+++ b/tools/cli/types_test.go
@@ -85,8 +85,9 @@ func TestCLIParsing(t *testing.T) {
 	)
 	rt(child1, "test child1", &options{})
 	rt(child1, "test child1 --set-me --simple-string=foo one", &options{SimpleString: "foo", SetMe: true}, "one")
+	rt(child1, "test child1 --set-me --simp=foo one", &options{SimpleString: "foo", SetMe: true}, "one")
 	rt(child1, "test child1 --set-me --simple-string= one", &options{SetMe: true}, "one")
-	rt(child1, "test child1 --int -3 --simple-string -s --float=3.3", &options{SimpleString: "-s", Int: -3, Float: 3.3})
+	rt(child1, "test child1 --int -3 --simple-s -s --float=3.3", &options{SimpleString: "-s", Int: -3, Float: 3.3})
 	rt(child1, "test child1 --list -3 -p --list one", &options{FromParent: 1, List: []string{"-3", "one"}})
 	rt(gc1, "test -p child1 -p gc1 xxx", &empty_options{}, "xxx")