diff --git a/bake/hcl.go b/bake/hcl.go
index de9d1840..e24110ae 100644
--- a/bake/hcl.go
+++ b/bake/hcl.go
@@ -133,6 +133,8 @@ type StaticConfig struct {
 	Variables []*Variable `hcl:"variable,block"`
 	Remain    hcl.Body    `hcl:",remain"`
 
+	attrs hcl.Attributes
+
 	defaults map[string]*hcl.Attribute
 	env      map[string]string
 	values   map[string]cty.Value
@@ -146,6 +148,9 @@ func mergeStaticConfig(scs []*StaticConfig) *StaticConfig {
 	sc := scs[0]
 	for _, s := range scs[1:] {
 		sc.Variables = append(sc.Variables, s.Variables...)
+		for k, v := range s.attrs {
+			sc.attrs[k] = v
+		}
 	}
 	return sc
 }
@@ -169,6 +174,12 @@ func (sc *StaticConfig) Values(withEnv bool) (map[string]cty.Value, error) {
 	sc.values = map[string]cty.Value{}
 	sc.progress = map[string]struct{}{}
 
+	for k := range sc.attrs {
+		if _, err := sc.resolveValue(k); err != nil {
+			return nil, err
+		}
+	}
+
 	for k := range sc.defaults {
 		if _, err := sc.resolveValue(k); err != nil {
 			return nil, err
@@ -192,10 +203,12 @@ func (sc *StaticConfig) resolveValue(name string) (v *cty.Value, err error) {
 		}
 	}()
 
-	def, ok := sc.defaults[name]
-
+	def, ok := sc.attrs[name]
 	if !ok {
-		return nil, errors.Errorf("undefined variable %q", name)
+		def, ok = sc.defaults[name]
+		if !ok {
+			return nil, errors.Errorf("undefined variable %q", name)
+		}
 	}
 
 	if def == nil {
@@ -233,7 +246,9 @@ func (sc *StaticConfig) resolveValue(name string) (v *cty.Value, err error) {
 		return nil, diags
 	}
 
-	if envv, ok := sc.env[name]; ok {
+	_, isVar := sc.defaults[name]
+
+	if envv, ok := sc.env[name]; ok && isVar {
 		if vv.Type().Equals(cty.Bool) {
 			b, err := strconv.ParseBool(envv)
 			if err != nil {
@@ -302,6 +317,16 @@ func parseHCLFile(dt []byte, fn string) (f *hcl.File, _ *StaticConfig, err error
 		return nil, nil, err
 	}
 
+	attrs, diags := f.Body.JustAttributes()
+	if diags.HasErrors() {
+		for _, d := range diags {
+			if d.Detail != "Blocks are not allowed here." {
+				return nil, nil, diags
+			}
+		}
+	}
+	sc.attrs = attrs
+
 	return f, &sc, nil
 }
 
diff --git a/bake/hcl_test.go b/bake/hcl_test.go
index 1429f025..70af0e3d 100644
--- a/bake/hcl_test.go
+++ b/bake/hcl_test.go
@@ -415,3 +415,101 @@ func TestHCLVariableCycle(t *testing.T) {
 	require.Error(t, err)
 	require.Contains(t, err.Error(), "variable cycle not allowed")
 }
+
+func TestHCLAttrs(t *testing.T) {
+	dt := []byte(`
+		FOO="abc"
+		BAR="attr-${FOO}def"
+		target "app" {
+			args = {
+				"v1": BAR
+			}
+		}
+		`)
+
+	c, err := ParseFile(dt, "docker-bake.hcl")
+	require.NoError(t, err)
+
+	require.Equal(t, 1, len(c.Targets))
+	require.Equal(t, c.Targets[0].Name, "app")
+	require.Equal(t, "attr-abcdef", c.Targets[0].Args["v1"])
+
+	// env does not apply if no variable
+	os.Setenv("FOO", "bar")
+	c, err = ParseFile(dt, "docker-bake.hcl")
+	require.NoError(t, err)
+
+	require.Equal(t, 1, len(c.Targets))
+	require.Equal(t, c.Targets[0].Name, "app")
+	require.Equal(t, "attr-abcdef", c.Targets[0].Args["v1"])
+	// attr-multifile
+}
+
+func TestHCLAttrsCustomType(t *testing.T) {
+	dt := []byte(`
+		platforms=["linux/arm64", "linux/amd64"]
+		target "app" {
+			platforms = platforms
+			args = {
+				"v1": platforms[0]
+			}
+		}
+		`)
+
+	c, err := ParseFile(dt, "docker-bake.hcl")
+	require.NoError(t, err)
+
+	require.Equal(t, 1, len(c.Targets))
+	require.Equal(t, c.Targets[0].Name, "app")
+	require.Equal(t, []string{"linux/arm64", "linux/amd64"}, c.Targets[0].Platforms)
+	require.Equal(t, "linux/arm64", c.Targets[0].Args["v1"])
+}
+
+func TestHCLMultiFileAttrs(t *testing.T) {
+	os.Unsetenv("FOO")
+	dt := []byte(`
+		variable "FOO" {
+			default = "abc"
+		}
+		target "app" {
+			args = {
+				v1 = "pre-${FOO}"
+			}
+		}
+		`)
+	dt2 := []byte(`
+		FOO="def"
+		`)
+
+	c, err := parseFiles([]File{
+		{Data: dt, Name: "c1.hcl"},
+		{Data: dt2, Name: "c2.hcl"},
+	})
+	require.NoError(t, err)
+	require.Equal(t, 1, len(c.Targets))
+	require.Equal(t, c.Targets[0].Name, "app")
+	require.Equal(t, "pre-def", c.Targets[0].Args["v1"])
+
+	os.Setenv("FOO", "ghi")
+
+	c, err = parseFiles([]File{
+		{Data: dt, Name: "c1.hcl"},
+		{Data: dt2, Name: "c2.hcl"},
+	})
+	require.NoError(t, err)
+
+	require.Equal(t, 1, len(c.Targets))
+	require.Equal(t, c.Targets[0].Name, "app")
+	require.Equal(t, "pre-ghi", c.Targets[0].Args["v1"])
+}
+
+func TestJSONAttributes(t *testing.T) {
+	dt := []byte(`{"FOO": "abc", "variable": {"BAR": {"default": "def"}}, "target": { "app": { "args": {"v1": "pre-${FOO}-${BAR}"}} } }`)
+
+	c, err := ParseFile(dt, "docker-bake.json")
+	require.NoError(t, err)
+
+	require.Equal(t, 1, len(c.Targets))
+	require.Equal(t, c.Targets[0].Name, "app")
+	require.Equal(t, "pre-abc-def", c.Targets[0].Args["v1"])
+}