diff --git a/Cargo.lock b/Cargo.lock
index 64b75e04a7d..358a6d77559 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -181,7 +181,7 @@ checksum = "ebb4bd301db2e2ca1f5be131c24eb8ebf2d9559bc3744419e93baf8ddea7e670"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.99",
 ]
 
 [[package]]
@@ -228,7 +228,7 @@ dependencies = [
  "regex",
  "rustc-hash",
  "shlex",
- "syn",
+ "syn 2.0.99",
 ]
 
 [[package]]
@@ -529,7 +529,7 @@ dependencies = [
  "proc-macro2",
  "pulldown-cmark",
  "quote",
- "syn",
+ "syn 2.0.102",
 ]
 
 [[package]]
@@ -582,7 +582,7 @@ dependencies = [
  "nom",
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.99",
 ]
 
 [[package]]
@@ -872,7 +872,7 @@ checksum = "1b4464d46ce68bfc7cb76389248c7c254def7baca8bece0693b02b83842c4c88"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.99",
 ]
 
 [[package]]
@@ -1427,7 +1427,7 @@ checksum = "6c6e1db7ed32c6c71b759497fae34bf7933636f75a251b9e736555da426f6442"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.99",
 ]
 
 [[package]]
@@ -1650,7 +1650,7 @@ checksum = "49e7bc1560b95a3c4a25d03de42fe76ca718ab92d1a22a55b9b4cf67b3ae635c"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.99",
 ]
 
 [[package]]
@@ -2311,7 +2311,7 @@ checksum = "a948666b637a0f465e8564c73e89d4dde00d72d4d473cc972f390fc3dcee7d9c"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.99",
 ]
 
 [[package]]
@@ -2445,7 +2445,7 @@ dependencies = [
  "pest_meta",
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.99",
 ]
 
 [[package]]
@@ -2926,7 +2926,7 @@ checksum = "e0cd7e117be63d3c3678776753929474f3b04a43a080c744d6b0ae2a8c28e222"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.99",
 ]
 
 [[package]]
@@ -3133,7 +3133,7 @@ dependencies = [
  "proc-macro2",
  "quote",
  "rustversion",
- "syn",
+ "syn 2.0.99",
 ]
 
 [[package]]
@@ -3175,6 +3175,16 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "syn"
+version = "2.0.102"
+source = "git+https://github.com/dtolnay/syn?rev=7680cb0c1d7cbf812118081dbcdfe5bc67083488#7680cb0c1d7cbf812118081dbcdfe5bc67083488"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
 [[package]]
 name = "sys-locale"
 version = "0.3.1"
@@ -3296,7 +3306,7 @@ checksum = "46c3384250002a6d5af4d114f2845d37b57521033f30d5c3f46c4d70e1197533"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.99",
 ]
 
 [[package]]
@@ -3468,7 +3478,7 @@ checksum = "ac73887f47b9312552aa90ef477927ff014d63d1920ca8037c6c1951eab64bb1"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.99",
 ]
 
 [[package]]
@@ -3832,7 +3842,7 @@ dependencies = [
  "once_cell",
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.99",
  "wasm-bindgen-shared",
 ]
 
@@ -3854,7 +3864,7 @@ checksum = "e94f17b526d0a461a191c78ea52bbce64071ed5c04c9ffe424dcb38f74171bb7"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.99",
  "wasm-bindgen-backend",
  "wasm-bindgen-shared",
 ]
@@ -4164,7 +4174,7 @@ checksum = "fa4f8080344d4671fb4e831a13ad1e68092748387dfc4f55e356242fae12ce3e"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.99",
 ]
 
 [[package]]
diff --git a/Cargo.toml b/Cargo.toml
index 8af48eec47b..753b02738ce 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -14,14 +14,14 @@ members = [
 repository = "https://github.com/clap-rs/clap"
 license = "MIT OR Apache-2.0"
 edition = "2021"
-rust-version = "1.74"  # MSRV
+rust-version = "1.74" # MSRV
 include = [
   "build.rs",
   "src/**/*",
   "Cargo.toml",
   "LICENSE*",
   "README.md",
-  "examples/**/*"
+  "examples/**/*",
 ]
 
 [workspace.lints.rust]
@@ -32,6 +32,8 @@ unsafe_op_in_unsafe_fn = "warn"
 unused_lifetimes = "warn"
 unused_macro_rules = "warn"
 unused_qualifications = "warn"
+# For testing with default_field_values
+unexpected_cfgs = { level = "warn", check-cfg = ['cfg(nightly)'] }
 
 [workspace.lints.clippy]
 bool_assert_comparison = "allow"
@@ -63,7 +65,7 @@ invalid_upcast_comparisons = "warn"
 large_digit_groups = "warn"
 large_stack_arrays = "warn"
 large_types_passed_by_value = "warn"
-let_and_return = "allow"  # sometimes good to name what you are returning
+let_and_return = "allow"                 # sometimes good to name what you are returning
 linkedlist = "warn"
 lossy_float_literal = "warn"
 macro_use_imports = "warn"
@@ -112,13 +114,7 @@ name = "clap"
 version = "4.5.40"
 description = "A simple to use, efficient, and full-featured Command Line Argument Parser"
 categories = ["command-line-interface"]
-keywords = [
-  "argument",
-  "cli",
-  "arg",
-  "parser",
-  "parse"
-]
+keywords = ["argument", "cli", "arg", "parser", "parse"]
 repository.workspace = true
 license.workspace = true
 edition.workspace = true
@@ -136,30 +132,23 @@ features = ["unstable-doc"]
 shared-version = true
 tag-name = "v{{version}}"
 pre-release-replacements = [
-  {file="CHANGELOG.md", search="Unreleased", replace="{{version}}", min=1},
-  {file="CHANGELOG.md", search="\\.\\.\\.HEAD", replace="...{{tag_name}}", exactly=1},
-  {file="CHANGELOG.md", search="ReleaseDate", replace="{{date}}", min=1},
-  {file="CHANGELOG.md", search="<!-- next-header -->", replace="<!-- next-header -->\n## [Unreleased] - ReleaseDate\n", exactly=1},
-  {file="CHANGELOG.md", search="<!-- next-url -->", replace="<!-- next-url -->\n[Unreleased]: https://github.com/clap-rs/clap/compare/{{tag_name}}...HEAD", exactly=1},
-  {file="CITATION.cff", search="^date-released: ....-..-..", replace="date-released: {{date}}"},
-  {file="CITATION.cff", search="^version: .+\\..+\\..+", replace="version: {{version}}"},
-  {file="src/lib.rs", search="blob/v.+\\..+\\..+/CHANGELOG.md", replace="blob/v{{version}}/CHANGELOG.md", exactly=1},
+  { file = "CHANGELOG.md", search = "Unreleased", replace = "{{version}}", min = 1 },
+  { file = "CHANGELOG.md", search = "\\.\\.\\.HEAD", replace = "...{{tag_name}}", exactly = 1 },
+  { file = "CHANGELOG.md", search = "ReleaseDate", replace = "{{date}}", min = 1 },
+  { file = "CHANGELOG.md", search = "<!-- next-header -->", replace = "<!-- next-header -->\n## [Unreleased] - ReleaseDate\n", exactly = 1 },
+  { file = "CHANGELOG.md", search = "<!-- next-url -->", replace = "<!-- next-url -->\n[Unreleased]: https://github.com/clap-rs/clap/compare/{{tag_name}}...HEAD", exactly = 1 },
+  { file = "CITATION.cff", search = "^date-released: ....-..-..", replace = "date-released: {{date}}" },
+  { file = "CITATION.cff", search = "^version: .+\\..+\\..+", replace = "version: {{version}}" },
+  { file = "src/lib.rs", search = "blob/v.+\\..+\\..+/CHANGELOG.md", replace = "blob/v{{version}}/CHANGELOG.md", exactly = 1 },
 ]
 
 [features]
-default = [
-  "std",
-  "color",
-  "help",
-  "usage",
-  "error-context",
-  "suggestions",
-]
-debug = ["clap_builder/debug", "clap_derive?/debug"] # Enables debug messages
-unstable-doc = ["clap_builder/unstable-doc", "derive"] # for docs.rs
+default = ["std", "color", "help", "usage", "error-context", "suggestions"]
+debug = ["clap_builder/debug", "clap_derive?/debug"]                        # Enables debug messages
+unstable-doc = ["clap_builder/unstable-doc", "derive"]                      # for docs.rs
 
 # Used in default
-std = ["clap_builder/std"] # support for no_std in a backwards-compatible way
+std = ["clap_builder/std"]                     # support for no_std in a backwards-compatible way
 color = ["clap_builder/color"]
 help = ["clap_builder/help"]
 usage = ["clap_builder/usage"]
@@ -167,18 +156,29 @@ error-context = ["clap_builder/error-context"]
 suggestions = ["clap_builder/suggestions"]
 
 # Optional
-deprecated = ["clap_builder/deprecated", "clap_derive?/deprecated"] # Guided experience to prepare for next breaking release (at different stages of development, this may become default)
+deprecated = [
+  "clap_builder/deprecated",
+  "clap_derive?/deprecated",
+] # Guided experience to prepare for next breaking release (at different stages of development, this may become default)
 derive = ["dep:clap_derive"]
-cargo = ["clap_builder/cargo"] # Disable if you're not using Cargo, enables Cargo-env-var-dependent macros
+cargo = [
+  "clap_builder/cargo",
+] # Disable if you're not using Cargo, enables Cargo-env-var-dependent macros
 wrap_help = ["clap_builder/wrap_help"]
 env = ["clap_builder/env"] # Use environment variables during arg parsing
-unicode = ["clap_builder/unicode"]  # Support for unicode characters in arguments and help messages
-string = ["clap_builder/string"]  # Allow runtime generated strings
+unicode = [
+  "clap_builder/unicode",
+] # Support for unicode characters in arguments and help messages
+string = ["clap_builder/string"] # Allow runtime generated strings
 
 # In-work features
-unstable-v5 = ["clap_builder/unstable-v5", "clap_derive?/unstable-v5", "deprecated"]
+unstable-v5 = [
+  "clap_builder/unstable-v5",
+  "clap_derive?/unstable-v5",
+  "deprecated",
+]
 unstable-ext = ["clap_builder/unstable-ext"]
-unstable-styles = ["clap_builder/unstable-styles"]  # deprecated
+unstable-styles = ["clap_builder/unstable-styles"] # deprecated
 unstable-derive-ui-tests = []
 unstable-markdown = ["clap_derive/unstable-markdown"]
 
@@ -193,7 +193,11 @@ clap_derive = { path = "./clap_derive", version = "=4.5.40", optional = true }
 trybuild = "1.0.91"
 rustversion = "1.0.15"
 # Cutting out `filesystem` feature
-trycmd = { version = "0.15.3", default-features = false, features = ["color-auto", "diff", "examples"] }
+trycmd = { version = "0.15.3", default-features = false, features = [
+  "color-auto",
+  "diff",
+  "examples",
+] }
 jiff = "0.2.3"
 snapbox = { version = "0.6.16", features = ["term-svg"] }
 shlex = "1.3.0"
diff --git a/clap_derive/Cargo.toml b/clap_derive/Cargo.toml
index 6db87ef5f99..e3e85e375f0 100644
--- a/clap_derive/Cargo.toml
+++ b/clap_derive/Cargo.toml
@@ -2,14 +2,11 @@
 name = "clap_derive"
 version = "4.5.40"
 description = "Parse command line argument by defining a struct, derive crate."
-categories = ["command-line-interface", "development-tools::procedural-macro-helpers"]
-keywords = [
-  "clap",
-  "cli",
-  "parse",
-  "derive",
-  "proc_macro"
+categories = [
+  "command-line-interface",
+  "development-tools::procedural-macro-helpers",
 ]
+keywords = ["clap", "cli", "parse", "derive", "proc_macro"]
 repository.workspace = true
 license.workspace = true
 edition.workspace = true
@@ -30,12 +27,15 @@ proc-macro = true
 bench = false
 
 [dependencies]
-syn = { version = "2.0.8", features = ["full"] }
+# https://github.com/dtolnay/syn/pull/1870
+syn = { version = "2.0.8", features = [
+  "full",
+], git = "https://github.com/dtolnay/syn", rev = "7680cb0c1d7cbf812118081dbcdfe5bc67083488" }
 quote = "1.0.9"
 proc-macro2 = "1.0.69"
 heck = "0.5.0"
-pulldown-cmark = { version = "0.13.0", default-features = false, optional = true}
-anstyle = {version ="1.0.10", optional = true}
+pulldown-cmark = { version = "0.13.0", default-features = false, optional = true }
+anstyle = { version = "1.0.10", optional = true }
 
 [features]
 default = []
diff --git a/clap_derive/src/item.rs b/clap_derive/src/item.rs
index ab32918e5f4..1f761df9009 100644
--- a/clap_derive/src/item.rs
+++ b/clap_derive/src/item.rs
@@ -21,7 +21,9 @@ use syn::DeriveInput;
 use syn::{self, ext::IdentExt, spanned::Spanned, Attribute, Field, Ident, LitStr, Type, Variant};
 
 use crate::attr::{AttrKind, AttrValue, ClapAttr, MagicAttrName};
-use crate::utils::{extract_doc_comment, format_doc_comment, inner_type, is_simple_ty, Sp, Ty};
+use crate::utils::{
+    extract_doc_comment, format_doc_comment, inner_type, is_simple_ty, DefaultField, Sp, Ty,
+};
 
 /// Default casing style for generated arguments.
 pub(crate) const DEFAULT_CASING: CasingStyle = CasingStyle::Kebab;
@@ -34,7 +36,7 @@ pub(crate) struct Item {
     name: Name,
     casing: Sp<CasingStyle>,
     env_casing: Sp<CasingStyle>,
-    ty: Option<Type>,
+    pub(crate) ty: Option<Type>,
     doc_comment: Vec<Method>,
     methods: Vec<Method>,
     deprecations: Vec<Deprecation>,
@@ -204,16 +206,35 @@ impl Item {
         let name = field.ident.clone().unwrap();
         let ident = field.ident.clone().unwrap();
         let span = field.span();
-        let ty = Ty::from_syn_ty(&field.ty);
+        let default_field = DefaultField::from_field_type(field.ty.clone());
+        let ty = Ty::from_syn_ty(&default_field.ty);
         let kind = Sp::new(Kind::Arg(ty), span);
+        let default_value_method = if let Some((_, expr)) = default_field.default {
+            let ty = &default_field.ty;
+            let val = quote_spanned!(expr.span()=> {
+                static DEFAULT_VALUE: ::std::sync::OnceLock<String> = ::std::sync::OnceLock::new();
+                let s = DEFAULT_VALUE.get_or_init(|| {
+                    let val: #ty = #expr;
+                    ::std::string::ToString::to_string(&val)
+                });
+                let s: &'static str = &*s;
+                s
+            });
+            let raw_ident = Ident::new("default_value", expr.span());
+            let method = Method::new(raw_ident, val);
+            Some(method)
+        } else {
+            None
+        };
         let mut res = Self::new(
             Name::Derived(name),
             ident,
-            Some(field.ty.clone()),
+            Some(default_field.ty),
             struct_casing,
             env_casing,
             kind,
         );
+        res.methods.extend(default_value_method);
         let parsed_attrs = ClapAttr::parse_all(&field.attrs)?;
         res.infer_kind(&parsed_attrs)?;
         res.push_attrs(&parsed_attrs)?;
@@ -1215,7 +1236,7 @@ impl Kind {
     }
 }
 
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 pub(crate) struct Method {
     name: Ident,
     args: TokenStream,
diff --git a/clap_derive/src/utils/default_field_value.rs b/clap_derive/src/utils/default_field_value.rs
new file mode 100644
index 00000000000..44b5fade824
--- /dev/null
+++ b/clap_derive/src/utils/default_field_value.rs
@@ -0,0 +1,49 @@
+//! Support for named fields with default field values
+
+use syn::{
+    parse::{Parse, ParseStream},
+    Expr, Token, Type,
+};
+
+pub(crate) struct DefaultField {
+    pub(crate) ty: Type,
+    /// Default value: `field_name: i32 = 1`
+    ///
+    /// `#![feature(default_field_values)]`
+    pub(crate) default: Option<(Token![=], Expr)>,
+}
+
+impl Parse for DefaultField {
+    fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
+        let field = input.parse()?;
+        let default = if input.peek(Token![=]) {
+            let eq_token = input.parse()?;
+            Some((eq_token, input.parse()?))
+        } else {
+            None
+        };
+
+        Ok(Self { ty: field, default })
+    }
+}
+
+impl DefaultField {
+    pub(crate) fn from_field_type(ty: Type) -> Self {
+        match ty {
+            Type::Verbatim(stream) => {
+                if let Ok(parsed) = syn::parse2(stream.clone()) {
+                    parsed
+                } else {
+                    Self {
+                        ty: Type::Verbatim(stream),
+                        default: None,
+                    }
+                }
+            }
+            other => Self {
+                ty: other,
+                default: None,
+            },
+        }
+    }
+}
diff --git a/clap_derive/src/utils/mod.rs b/clap_derive/src/utils/mod.rs
index c7e4b8e5358..8e0c98ae830 100644
--- a/clap_derive/src/utils/mod.rs
+++ b/clap_derive/src/utils/mod.rs
@@ -1,9 +1,11 @@
 pub(crate) mod error;
 
+mod default_field_value;
 mod doc_comments;
 mod spanned;
 mod ty;
 
+pub(crate) use default_field_value::DefaultField;
 pub(crate) use doc_comments::extract_doc_comment;
 pub(crate) use doc_comments::format_doc_comment;
 
diff --git a/clap_derive/src/utils/ty.rs b/clap_derive/src/utils/ty.rs
index c38344c8dda..8a17882db40 100644
--- a/clap_derive/src/utils/ty.rs
+++ b/clap_derive/src/utils/ty.rs
@@ -1,5 +1,7 @@
 //! Special types handling
 
+use crate::utils::DefaultField;
+
 use super::spanned::Sp;
 
 use syn::{
@@ -22,6 +24,10 @@ pub(crate) enum Ty {
 impl Ty {
     pub(crate) fn from_syn_ty(ty: &Type) -> Sp<Self> {
         use self::Ty::{Option, OptionOption, OptionVec, OptionVecVec, Other, Unit, Vec, VecVec};
+        // TODO: Avoid clone here.
+        // Hack: If the type has a default field value, just ignore it.
+        let ty = DefaultField::from_field_type(ty.clone()).ty;
+        let ty = &ty;
         let t = |kind| Sp::new(kind, ty.span());
 
         if is_unit_ty(ty) {
@@ -57,6 +63,11 @@ impl Ty {
 
 pub(crate) fn inner_type(field_ty: &Type) -> &Type {
     let ty = Ty::from_syn_ty(field_ty);
+    // TODO: Avoid clone here.
+    // Hack: If the type has a default field value, just ignore it.
+    let field_ty = DefaultField::from_field_type(field_ty.clone()).ty;
+    // Obviously, this is really awful, and will be changed before merging.
+    let field_ty = Box::leak(Box::new(field_ty));
     match *ty {
         Ty::Vec | Ty::Option => sub_type(field_ty).unwrap_or(field_ty),
         Ty::OptionOption | Ty::OptionVec | Ty::VecVec => {
diff --git a/tests/default_field_values/main.rs b/tests/default_field_values/main.rs
new file mode 100644
index 00000000000..ab28e948830
--- /dev/null
+++ b/tests/default_field_values/main.rs
@@ -0,0 +1,11 @@
+//! To run this test, use:
+//! ```
+//! RUSTFLAGS="--cfg=nightly" cargo +nightly test --test default_field_values --features derive --features help --features usage
+//! ```
+#![cfg(nightly)]
+#![feature(default_field_values)]
+#![cfg(feature = "derive")]
+#![cfg(feature = "help")]
+#![cfg(feature = "usage")]
+
+mod tests;
diff --git a/tests/default_field_values/tests.rs b/tests/default_field_values/tests.rs
new file mode 100644
index 00000000000..96631450cd6
--- /dev/null
+++ b/tests/default_field_values/tests.rs
@@ -0,0 +1,32 @@
+//! A module for the actual test.
+//!
+//! This is necessary because rustc will choke if we try and inline this module, because the (stable) parser knows
+//! that default field values are unstable, and complains even for `cfg()`ed out occurrences.
+
+use clap::{CommandFactory, Parser};
+
+// Copy of the same from tests/derive/util.rs
+pub(crate) fn get_long_help<T: CommandFactory>() -> String {
+    let output = <T as CommandFactory>::command()
+        .render_long_help()
+        .to_string();
+
+    eprintln!("\n%%% LONG_HELP %%%:=====\n{output}\n=====\n");
+    eprintln!("\n%%% LONG_HELP (DEBUG) %%%:=====\n{output:?}\n=====\n");
+
+    output
+}
+
+#[test]
+fn default_field_value() {
+    #[derive(Parser, Debug, PartialEq)]
+    struct Opt {
+            arg: i32 = 3,
+        }
+
+    assert_eq!(Opt { arg: 3 }, Opt::try_parse_from(["test"]).unwrap());
+    assert_eq!(Opt { arg: 1 }, Opt::try_parse_from(["test", "1"]).unwrap());
+
+    let help = get_long_help::<Opt>();
+    assert!(help.contains("[default: 3]"));
+}