diff --git a/Cargo.lock b/Cargo.lock
index 087cd5b16..04b1b4659 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1523,6 +1523,7 @@ dependencies = [
  "git-branchless-testing",
  "git-branchless-undo",
  "git-record",
+ "git2-ext",
  "insta",
  "itertools 0.10.5",
  "lazy_static",
@@ -1611,6 +1612,7 @@ dependencies = [
  "git-branchless-testing",
  "git-record",
  "git2",
+ "git2-ext",
  "indicatif",
  "insta",
  "itertools 0.10.5",
@@ -1908,6 +1910,21 @@ dependencies = [
  "url",
 ]
 
+[[package]]
+name = "git2-ext"
+version = "0.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a02e722c7e38969577e2f7a59b13fde0ee93e32b21d64bcbc3befedb9dd57a8b"
+dependencies = [
+ "bstr",
+ "git2",
+ "itertools 0.10.5",
+ "log",
+ "shlex",
+ "tempfile",
+ "which",
+]
+
 [[package]]
 name = "glob"
 version = "0.3.1"
@@ -3968,6 +3985,17 @@ dependencies = [
  "wasm-bindgen",
 ]
 
+[[package]]
+name = "which"
+version = "4.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2441c784c52b289a054b7201fc93253e288f094e2f4be9058343127c4226a269"
+dependencies = [
+ "either",
+ "libc",
+ "once_cell",
+]
+
 [[package]]
 name = "winapi"
 version = "0.3.9"
diff --git a/git-branchless-lib/Cargo.toml b/git-branchless-lib/Cargo.toml
index 3bb3c7621..b21d9cd98 100644
--- a/git-branchless-lib/Cargo.toml
+++ b/git-branchless-lib/Cargo.toml
@@ -57,6 +57,7 @@ eyre = "0.6.8"
 futures = "0.3.28"
 git-record = { version = "0.3", path = "../git-record" }
 git2 = { version = "0.17.2", default-features = false }
+git2-ext = "0.6.0"
 indicatif = { version = "0.17.5", features = ["improved_unicode"] }
 itertools = "0.10.3"
 lazy_static = "1.4.0"
diff --git a/git-branchless-lib/src/core/rewrite/execute.rs b/git-branchless-lib/src/core/rewrite/execute.rs
index 98186fcda..46c04ca74 100644
--- a/git-branchless-lib/src/core/rewrite/execute.rs
+++ b/git-branchless-lib/src/core/rewrite/execute.rs
@@ -15,7 +15,7 @@ use crate::core::formatting::Pluralize;
 use crate::core::repo_ext::RepoExt;
 use crate::git::{
     BranchType, CategorizedReferenceName, GitRunInfo, MaybeZeroOid, NonZeroOid, ReferenceName,
-    Repo, ResolvedReferenceInfo,
+    Repo, ResolvedReferenceInfo, SignOption,
 };
 use crate::util::{ExitCode, EyreExitOr};
 
@@ -435,7 +435,8 @@ mod in_memory {
     use crate::core::rewrite::move_branches;
     use crate::core::rewrite::plan::{OidOrLabel, RebaseCommand, RebasePlan};
     use crate::git::{
-        CherryPickFastError, CherryPickFastOptions, GitRunInfo, MaybeZeroOid, NonZeroOid, Repo,
+        self, CherryPickFastError, CherryPickFastOptions, GitRunInfo, MaybeZeroOid, NonZeroOid,
+        Repo,
     };
     use crate::util::EyreExitOr;
 
@@ -498,6 +499,7 @@ mod in_memory {
             force_on_disk: _,
             resolve_merge_conflicts: _, // May be needed once we can resolve merge conflicts in memory.
             check_out_commit_options: _, // Caller is responsible for checking out to new HEAD.
+            sign_option,
         } = options;
 
         let mut current_oid = rebase_plan.first_dest_oid;
@@ -535,6 +537,8 @@ mod in_memory {
             .count();
         let (effects, progress) = effects.start_operation(OperationType::RebaseCommits);
 
+        let signer = git::get_signer(&repo, sign_option)?;
+
         for command in rebase_plan.commands.iter() {
             match command {
                 RebaseCommand::CreateLabel { label_name } => {
@@ -628,12 +632,12 @@ mod in_memory {
                     };
                     let rebased_commit_oid = repo
                         .create_commit(
-                            None,
                             &commit_to_apply.get_author(),
                             &committer_signature,
                             commit_message,
                             &commit_tree,
                             vec![&current_commit],
+                            signer.as_deref(),
                         )
                         .wrap_err("Applying rebased commit")?;
 
@@ -748,12 +752,12 @@ mod in_memory {
                     };
                     let rebased_commit_oid = repo
                         .create_commit(
-                            None,
                             &replacement_commit.get_author(),
                             &committer_signature,
                             replacement_commit_message,
                             &replacement_tree,
                             parents.iter().collect(),
+                            signer.as_deref(),
                         )
                         .wrap_err("Applying rebased commit")?;
 
@@ -864,6 +868,7 @@ mod in_memory {
             force_on_disk: _,
             resolve_merge_conflicts: _,
             check_out_commit_options,
+            sign_option: _,
         } = options;
 
         // Note that if an OID has been mapped to multiple other OIDs, then the last
@@ -959,6 +964,7 @@ mod on_disk {
             force_on_disk: _,
             resolve_merge_conflicts: _,
             check_out_commit_options: _, // Checkout happens after rebase has concluded.
+            sign_option,
         } = options;
 
         let (effects, _progress) = effects.start_operation(OperationType::InitializeRebase);
@@ -1073,6 +1079,16 @@ mod on_disk {
             )
         })?;
 
+        let gpg_sign_opt_file = rebase_state_dir.join("gpg_sign_opt");
+        if let Some(sign_flag) = sign_option.as_rebase_flag(repo)? {
+            std::fs::write(&gpg_sign_opt_file, sign_flag).wrap_err_with(|| {
+                format!(
+                    "Writing `gpg_sign_opt` to: {:?}",
+                    gpg_sign_opt_file.as_path()
+                )
+            })?;
+        }
+
         let end_file_path = rebase_state_dir.join("end");
         std::fs::write(
             end_file_path.as_path(),
@@ -1132,6 +1148,7 @@ mod on_disk {
             force_on_disk: _,
             resolve_merge_conflicts: _,
             check_out_commit_options: _, // Checkout happens after rebase has concluded.
+            sign_option: _,
         } = options;
 
         match write_rebase_state_to_disk(effects, git_run_info, repo, rebase_plan, options)? {
@@ -1176,6 +1193,9 @@ pub struct ExecuteRebasePlanOptions {
 
     /// If `HEAD` was moved, the options for checking out the new `HEAD` commit.
     pub check_out_commit_options: CheckOutCommitOptions,
+
+    /// GPG-sign commits.
+    pub sign_option: SignOption,
 }
 
 /// The result of executing a rebase plan.
@@ -1221,6 +1241,7 @@ pub fn execute_rebase_plan(
         force_on_disk,
         resolve_merge_conflicts,
         check_out_commit_options: _,
+        sign_option: _,
     } = options;
 
     if !force_on_disk {
diff --git a/git-branchless-lib/src/git/mod.rs b/git-branchless-lib/src/git/mod.rs
index 62f4a64c7..69529148f 100644
--- a/git-branchless-lib/src/git/mod.rs
+++ b/git-branchless-lib/src/git/mod.rs
@@ -8,6 +8,7 @@ mod oid;
 mod reference;
 mod repo;
 mod run;
+mod sign;
 mod snapshot;
 mod status;
 mod test;
@@ -27,6 +28,7 @@ pub use repo::{
     Time,
 };
 pub use run::{GitRunInfo, GitRunOpts, GitRunResult};
+pub use sign::{get_signer, SignOption};
 pub use snapshot::{WorkingCopyChangesType, WorkingCopySnapshot};
 pub use status::{FileMode, FileStatus, StatusEntry};
 pub use test::{
diff --git a/git-branchless-lib/src/git/repo.rs b/git-branchless-lib/src/git/repo.rs
index 5a8088b32..99a2830ed 100644
--- a/git-branchless-lib/src/git/repo.rs
+++ b/git-branchless-lib/src/git/repo.rs
@@ -24,6 +24,7 @@ use chrono::NaiveDateTime;
 use cursive::theme::BaseColor;
 use cursive::utils::markup::StyledString;
 use git2::DiffOptions;
+use git2_ext::ops::Sign;
 use itertools::Itertools;
 use thiserror::Error;
 use tracing::{instrument, warn};
@@ -1152,31 +1153,81 @@ impl Repo {
     }
 
     /// Create a new commit.
-    #[instrument]
+    #[instrument(skip(signer))]
     pub fn create_commit(
         &self,
-        update_ref: Option<&str>,
         author: &Signature,
         committer: &Signature,
         message: &str,
         tree: &Tree,
         parents: Vec<&Commit>,
+        signer: Option<&dyn Sign>,
     ) -> Result<NonZeroOid> {
         let parents = parents
             .iter()
             .map(|commit| &commit.inner)
             .collect::<Vec<_>>();
-        let oid = self
-            .inner
-            .commit(
-                update_ref,
-                &author.inner,
-                &committer.inner,
-                message,
-                &tree.inner,
-                parents.as_slice(),
-            )
-            .map_err(Error::CreateCommit)?;
+        let oid = git2_ext::ops::commit(
+            &self.inner,
+            &author.inner,
+            &committer.inner,
+            message,
+            &tree.inner,
+            parents.as_slice(),
+            signer,
+        )
+        .map_err(Error::CreateCommit)?;
+        Ok(make_non_zero_oid(oid))
+    }
+
+    /// Amend a commit with all non-`None` values
+    #[instrument(skip(signer))]
+    pub fn amend_commit(
+        &self,
+        commit_to_amend: &Commit,
+        author: Option<&Signature>,
+        committer: Option<&Signature>,
+        message: Option<&str>,
+        tree: Option<&Tree>,
+        signer: Option<&dyn Sign>,
+    ) -> Result<NonZeroOid> {
+        macro_rules! owning_unwrap_or {
+            ($name:ident, $value_source:expr) => {
+                let owned_value;
+                let $name = if let Some(value) = $name {
+                    value
+                } else {
+                    owned_value = $value_source;
+                    &owned_value
+                };
+            };
+        }
+        owning_unwrap_or!(author, commit_to_amend.get_author());
+        owning_unwrap_or!(committer, commit_to_amend.get_committer());
+        owning_unwrap_or!(
+            message,
+            commit_to_amend
+                .inner
+                .message_raw()
+                .ok_or(Error::DecodeUtf8 {
+                    item: "raw message",
+                })?
+        );
+        owning_unwrap_or!(tree, commit_to_amend.get_tree()?);
+
+        let parents = commit_to_amend.get_parents();
+        let parents = parents.iter().map(|parent| &parent.inner).collect_vec();
+
+        let oid = git2_ext::ops::commit(
+            &self.inner,
+            &author.inner,
+            &committer.inner,
+            message,
+            &tree.inner,
+            parents.as_slice(),
+            signer,
+        )
+        .map_err(Error::Amend)?;
         Ok(make_non_zero_oid(oid))
     }
 
@@ -1365,12 +1416,12 @@ impl Repo {
             vec![]
         };
         let dehydrated_commit_oid = self.create_commit(
-            None,
             &signature,
             &signature,
             &message,
             &dehydrated_tree,
             parents.iter().collect_vec(),
+            None,
         )?;
         let dehydrated_commit = self.find_commit_or_fail(dehydrated_commit_oid)?;
         Ok(dehydrated_commit)
diff --git a/git-branchless-lib/src/git/sign.rs b/git-branchless-lib/src/git/sign.rs
new file mode 100644
index 000000000..de550b94b
--- /dev/null
+++ b/git-branchless-lib/src/git/sign.rs
@@ -0,0 +1,108 @@
+use tracing::instrument;
+
+use super::{repo::Result, Repo, RepoError};
+
+/// GPG-signing option.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum SignOption {
+    /// Sign commits conditionally based on the `commit.gpgsign` configuration and
+    /// and the key `user.signingkey`.
+    UseConfig,
+    /// Sign commits using the key from `user.signingkey` configuration.
+    UseConfigKey,
+    /// Sign commits using the provided signing key.
+    KeyOverride(String),
+    /// Do not sign commits.
+    Disable,
+}
+
+impl SignOption {
+    /// GPG-signing flag to pass to Git.
+    pub fn as_git_flag(&self) -> Option<String> {
+        match self {
+            Self::UseConfig => None,
+            Self::UseConfigKey => Some("--gpg-sign".to_string()),
+            Self::KeyOverride(keyid) => Some(format!("--gpg-sign={}", keyid)),
+            Self::Disable => Some("--no-gpg-sign".to_string()),
+        }
+    }
+
+    /// GPG-signing flag to use for interactive rebase
+    pub fn as_rebase_flag(&self, repo: &Repo) -> Result<Option<String>> {
+        Ok(match self {
+            Self::UseConfig => {
+                let config = repo.inner.config().map_err(RepoError::ReadConfig)?;
+                match config.get_bool("commit.gpgsign").ok() {
+                    Some(true) => Some("-S".to_string()),
+                    Some(false) | None => None,
+                }
+            }
+            Self::UseConfigKey => Some("-S".to_string()),
+            Self::KeyOverride(keyid) => Some(format!("-S{}", keyid)),
+            Self::Disable => None,
+        })
+    }
+}
+
+/// Get commit signer configured from CLI arguments and repository configurations.
+#[instrument]
+pub fn get_signer(
+    repo: &Repo,
+    option: &SignOption,
+) -> Result<Option<Box<dyn git2_ext::ops::Sign>>> {
+    match option {
+        SignOption::UseConfig | SignOption::UseConfigKey => {
+            let config = repo.inner.config().map_err(RepoError::ReadConfig)?;
+            if *option == SignOption::UseConfig {
+                if config.get_bool("commit.gpgsign").ok() == Some(false) {
+                    return Ok(None);
+                }
+            }
+            let signer = git2_ext::ops::UserSign::from_config(&repo.inner, &config)
+                .map_err(RepoError::ReadConfig)?;
+            Ok(Some(Box::new(signer) as Box<dyn git2_ext::ops::Sign>))
+        }
+        SignOption::KeyOverride(keyid) => {
+            let config = repo.inner.config().map_err(RepoError::ReadConfig)?;
+            let format = config
+                .get_string("gpg.format")
+                .unwrap_or_else(|_| "openpgp".to_owned());
+            let signer = match format.as_str() {
+                "openpgp" => {
+                    let program = config
+                        .get_string("gpg.openpgp.program")
+                        .or_else(|_| config.get_string("gpg.program"))
+                        .unwrap_or_else(|_| "gpg".to_owned());
+
+                    Box::new(git2_ext::ops::GpgSign::new(program, keyid.to_string()))
+                        as Box<dyn git2_ext::ops::Sign>
+                }
+                "x509" => {
+                    let program = config
+                        .get_string("gpg.x509.program")
+                        .unwrap_or_else(|_| "gpgsm".to_owned());
+
+                    Box::new(git2_ext::ops::GpgSign::new(program, keyid.to_string()))
+                        as Box<dyn git2_ext::ops::Sign>
+                }
+                "ssh" => {
+                    let program = config
+                        .get_string("gpg.ssh.program")
+                        .unwrap_or_else(|_| "ssh-keygen".to_owned());
+
+                    Box::new(git2_ext::ops::SshSign::new(program, keyid.to_string()))
+                        as Box<dyn git2_ext::ops::Sign>
+                }
+                format => {
+                    return Err(RepoError::ReadConfig(git2::Error::new(
+                        git2::ErrorCode::Invalid,
+                        git2::ErrorClass::Config,
+                        format!("invalid value for gpg.format: {}", format),
+                    )))
+                }
+            };
+            Ok(Some(signer))
+        }
+        SignOption::Disable => Ok(None),
+    }
+}
diff --git a/git-branchless-lib/src/git/snapshot.rs b/git-branchless-lib/src/git/snapshot.rs
index 148bce4f9..068e7f8aa 100644
--- a/git-branchless-lib/src/git/snapshot.rs
+++ b/git-branchless-lib/src/git/snapshot.rs
@@ -213,7 +213,7 @@ branchless: automated working copy snapshot
             parents
         };
         let commit_oid =
-            repo.create_commit(None, &signature, &signature, &message, &tree, parents)?;
+            repo.create_commit(&signature, &signature, &message, &tree, parents, None)?;
 
         Ok(WorkingCopySnapshot {
             base_commit: repo.find_commit_or_fail(commit_oid)?,
@@ -365,12 +365,12 @@ branchless: automated working copy snapshot
             }
         );
         let commit = repo.create_commit(
-            None,
             &signature,
             &signature,
             &message,
             &tree_unstaged,
             Vec::from_iter(head_commit),
+            None,
         )?;
         Ok(commit)
     }
@@ -452,7 +452,6 @@ branchless: automated working copy snapshot
             }
         );
         let commit_oid = repo.create_commit(
-            None,
             &signature,
             &signature,
             &message,
@@ -461,6 +460,7 @@ branchless: automated working copy snapshot
                 Some(parent_commit) => vec![parent_commit],
                 None => vec![],
             },
+            None,
         )?;
         Ok(commit_oid)
     }
diff --git a/git-branchless-lib/tests/test_rewrite_plan.rs b/git-branchless-lib/tests/test_rewrite_plan.rs
index 0cad96ab8..e47657444 100644
--- a/git-branchless-lib/tests/test_rewrite_plan.rs
+++ b/git-branchless-lib/tests/test_rewrite_plan.rs
@@ -15,6 +15,7 @@ use branchless::core::rewrite::{
     execute_rebase_plan, BuildRebasePlanOptions, ExecuteRebasePlanOptions, ExecuteRebasePlanResult,
     RebasePlan, RebasePlanBuilder, RepoResource,
 };
+use branchless::git::SignOption;
 use git_branchless_testing::{make_git, Git};
 
 #[test]
@@ -713,6 +714,7 @@ fn create_and_execute_plan(
             reset: false,
             render_smartlog: false,
         },
+        sign_option: SignOption::Disable,
     };
     let git_run_info = git.get_git_run_info();
     let result = execute_rebase_plan(
diff --git a/git-branchless-move/src/lib.rs b/git-branchless-move/src/lib.rs
index c988be41e..173e6e026 100644
--- a/git-branchless-move/src/lib.rs
+++ b/git-branchless-move/src/lib.rs
@@ -261,6 +261,7 @@ pub fn r#move(
         resolve_merge_conflicts,
         dump_rebase_constraints,
         dump_rebase_plan,
+        ref sign_options,
     } = *move_options;
     let now = SystemTime::now();
     let event_tx_id = event_log_db.make_transaction_id(now, "move")?;
@@ -471,6 +472,7 @@ pub fn r#move(
                 force_on_disk,
                 resolve_merge_conflicts,
                 check_out_commit_options: Default::default(),
+                sign_option: sign_options.to_owned().into(),
             };
             execute_rebase_plan(
                 effects,
diff --git a/git-branchless-opts/src/lib.rs b/git-branchless-opts/src/lib.rs
index df10ca5ac..cd658e617 100644
--- a/git-branchless-opts/src/lib.rs
+++ b/git-branchless-opts/src/lib.rs
@@ -91,6 +91,10 @@ pub struct MoveOptions {
     /// executing it.
     #[clap(action, long = "debug-dump-rebase-plan")]
     pub dump_rebase_plan: bool,
+
+    /// GPG-sign commits.
+    #[clap(flatten)]
+    pub sign_options: SignOptions,
 }
 
 /// Options for traversing commits.
@@ -178,6 +182,46 @@ pub struct SwitchOptions {
     pub target: Option<String>,
 }
 
+/// Options for signing commits
+#[derive(Args, Debug, Clone)]
+pub struct SignOptions {
+    /// GPG-sign commits. The `keyid` argument is optional and defaults to the committer
+    /// identity.
+    #[clap(
+        short = 'S',
+        long = "gpg-sign",
+        value_name = "keyid",
+        conflicts_with = "no_gpg_sign",
+        num_args(0..=1),
+        default_missing_value(""),
+    )]
+    pub gpg_sign: Option<String>,
+
+    /// Countermand `commit.gpgSign` configuration variable.
+    #[clap(long = "no-gpg-sign", conflicts_with = "gpg_sign")]
+    pub no_gpg_sign: bool,
+}
+
+impl From<SignOptions> for lib::git::SignOption {
+    fn from(value: SignOptions) -> Self {
+        let SignOptions {
+            gpg_sign,
+            no_gpg_sign,
+        } = value;
+        if no_gpg_sign {
+            Self::Disable
+        } else if let Some(keyid) = gpg_sign {
+            if keyid.as_str() != "" {
+                Self::KeyOverride(keyid)
+            } else {
+                Self::UseConfigKey
+            }
+        } else {
+            Self::UseConfig
+        }
+    }
+}
+
 /// Internal use.
 #[derive(Debug, Parser)]
 pub enum HookSubcommand {
@@ -320,6 +364,10 @@ pub struct RecordArgs {
     /// if any.
     #[clap(action, short = 'I', long = "insert")]
     pub insert: bool,
+
+    /// Options for signing commits.
+    #[clap(flatten)]
+    pub sign_options: SignOptions,
 }
 
 /// Display a nice graph of the commits you've recently worked on.
@@ -602,6 +650,10 @@ pub enum Command {
         /// use with `git rebase --autosquash`) targeting the supplied commit.
         #[clap(value_parser, long = "fixup", conflicts_with_all(&["messages", "discard"]))]
         commit_to_fixup: Option<Revset>,
+
+        /// GPG-sign commits.
+        #[clap(flatten)]
+        sign_options: SignOptions,
     },
 
     /// `smartlog` command.
diff --git a/git-branchless-record/src/lib.rs b/git-branchless-record/src/lib.rs
index 0f152eacc..64ff52017 100644
--- a/git-branchless-record/src/lib.rs
+++ b/git-branchless-record/src/lib.rs
@@ -31,7 +31,7 @@ use lib::core::rewrite::{
 };
 use lib::git::{
     process_diff_for_record, update_index, CategorizedReferenceName, FileMode, GitRunInfo,
-    MaybeZeroOid, NonZeroOid, Repo, ResolvedReferenceInfo, Stage, UpdateIndexCommand,
+    MaybeZeroOid, NonZeroOid, Repo, ResolvedReferenceInfo, SignOption, Stage, UpdateIndexCommand,
     WorkingCopyChangesType, WorkingCopySnapshot,
 };
 use lib::try_exit_code;
@@ -53,6 +53,7 @@ pub fn command_main(ctx: CommandContext, args: RecordArgs) -> EyreExitOr<()> {
         create,
         detach,
         insert,
+        sign_options,
     } = args;
     record(
         &effects,
@@ -62,6 +63,7 @@ pub fn command_main(ctx: CommandContext, args: RecordArgs) -> EyreExitOr<()> {
         create,
         detach,
         insert,
+        &sign_options.into(),
     )
 }
 
@@ -74,6 +76,7 @@ fn record(
     branch_name: Option<String>,
     detach: bool,
     insert: bool,
+    sign_option: &SignOption,
 ) -> EyreExitOr<()> {
     let now = SystemTime::now();
     let repo = Repo::from_dir(&git_run_info.working_directory)?;
@@ -147,19 +150,22 @@ fn record(
                 &snapshot,
                 event_tx_id,
                 message.as_deref(),
+                sign_option,
             )?);
         }
     } else {
-        let args = {
-            let mut args = vec!["commit"];
-            if let Some(message) = &message {
-                args.extend(["--message", message]);
-            }
-            if working_copy_changes_type == WorkingCopyChangesType::Unstaged {
-                args.push("--all");
-            }
-            args
-        };
+        let mut args = vec!["commit"];
+        if let Some(message) = &message {
+            args.extend(["--message", message]);
+        }
+        if working_copy_changes_type == WorkingCopyChangesType::Unstaged {
+            args.push("--all");
+        }
+        let sign_flag = sign_option.as_git_flag();
+        if let Some(flag) = &sign_flag {
+            args.push(flag);
+        }
+
         try_exit_code!(git_run_info.run_direct_no_wrapping(Some(event_tx_id), &args)?);
     }
 
@@ -209,7 +215,8 @@ fn record(
             effects,
             git_run_info,
             now,
-            event_tx_id
+            event_tx_id,
+            sign_option,
         )?);
     }
 
@@ -224,6 +231,7 @@ fn record_interactive(
     snapshot: &WorkingCopySnapshot,
     event_tx_id: EventTransactionId,
     message: Option<&str>,
+    sign_option: &SignOption,
 ) -> EyreExitOr<()> {
     let old_tree = snapshot.commit_stage0.get_tree()?;
     let new_tree = snapshot.commit_unstaged.get_tree()?;
@@ -332,13 +340,15 @@ fn record_interactive(
         &update_index_script,
     )?;
 
-    let args = {
-        let mut args = vec!["commit"];
-        if let Some(message) = message {
-            args.extend(["--message", message]);
-        }
-        args
-    };
+    let mut args = vec!["commit"];
+    if let Some(message) = message {
+        args.extend(["--message", message]);
+    }
+    let sign_flag = sign_option.as_git_flag();
+    if let Some(flag) = &sign_flag {
+        args.push(flag);
+    }
+
     git_run_info.run_direct_no_wrapping(Some(event_tx_id), &args)
 }
 
@@ -348,6 +358,7 @@ fn insert_before_siblings(
     git_run_info: &GitRunInfo,
     now: SystemTime,
     event_tx_id: EventTransactionId,
+    sign_option: &SignOption,
 ) -> EyreExitOr<()> {
     // Reopen the repository since references may have changed.
     let repo = Repo::from_dir(&git_run_info.working_directory)?;
@@ -475,6 +486,7 @@ To proceed anyways, run: git move -f -s 'siblings(.)",
         force_on_disk: false,
         resolve_merge_conflicts: false,
         check_out_commit_options: Default::default(),
+        sign_option: sign_option.to_owned(),
     };
     let result = execute_rebase_plan(
         effects,
diff --git a/git-branchless-reword/src/lib.rs b/git-branchless-reword/src/lib.rs
index a648b7ee2..b93521376 100644
--- a/git-branchless-reword/src/lib.rs
+++ b/git-branchless-reword/src/lib.rs
@@ -42,7 +42,7 @@ use lib::core::rewrite::{
 };
 use lib::git::{message_prettify, Commit, GitRunInfo, MaybeZeroOid, NonZeroOid, Repo};
 
-use git_branchless_opts::{ResolveRevsetOptions, Revset};
+use git_branchless_opts::{ResolveRevsetOptions, Revset, SignOptions};
 use git_branchless_revset::resolve_commits;
 
 /// The commit message(s) provided by the user.
@@ -67,6 +67,7 @@ pub fn reword(
     messages: InitialCommitMessages,
     git_run_info: &GitRunInfo,
     force_rewrite_public_commits: bool,
+    sign_options: SignOptions,
 ) -> EyreExitOr<()> {
     let repo = Repo::from_current_dir()?;
     let references_snapshot = repo.get_references_snapshot()?;
@@ -290,6 +291,7 @@ pub fn reword(
             reset: false,
             render_smartlog: false,
         },
+        sign_option: sign_options.into(),
     };
     let result = execute_rebase_plan(
         effects,
diff --git a/git-branchless-submit/src/phabricator.rs b/git-branchless-submit/src/phabricator.rs
index 2721093e4..5d4e03625 100644
--- a/git-branchless-submit/src/phabricator.rs
+++ b/git-branchless-submit/src/phabricator.rs
@@ -26,7 +26,9 @@ use lib::core::rewrite::{
     execute_rebase_plan, BuildRebasePlanError, BuildRebasePlanOptions, ExecuteRebasePlanOptions,
     ExecuteRebasePlanResult, RebasePlanBuilder, RebasePlanPermissions, RepoResource,
 };
-use lib::git::{Commit, GitRunInfo, MaybeZeroOid, NonZeroOid, Repo, RepoError, TestCommand};
+use lib::git::{
+    Commit, GitRunInfo, MaybeZeroOid, NonZeroOid, Repo, RepoError, SignOption, TestCommand,
+};
 use lib::try_exit_code;
 use lib::util::{ExitCode, EyreExitOr};
 use rayon::ThreadPoolBuilder;
@@ -359,6 +361,7 @@ impl Forge for PhabricatorForge<'_> {
                 render_smartlog: false,
                 ..Default::default()
             },
+            sign_option: SignOption::Disable,
         };
         let permissions =
             RebasePlanPermissions::verify_rewrite_set(self.dag, build_options, &commit_set)
@@ -608,6 +611,7 @@ Differential Revision: https://phabricator.example.com/D000$(git rev-list --coun
                 render_smartlog: false,
                 ..Default::default()
             },
+            sign_option: SignOption::Disable,
         };
         let permissions =
             RebasePlanPermissions::verify_rewrite_set(self.dag, build_options, &commit_set)
diff --git a/git-branchless-test/src/lib.rs b/git-branchless-test/src/lib.rs
index a1e3434ca..f8f8bcf4e 100644
--- a/git-branchless-test/src/lib.rs
+++ b/git-branchless-test/src/lib.rs
@@ -51,8 +51,9 @@ use lib::core::rewrite::{
 use lib::git::{
     get_latest_test_command_path, get_test_locks_dir, get_test_tree_dir, get_test_worktrees_dir,
     make_test_command_slug, Commit, ConfigRead, GitRunInfo, GitRunResult, MaybeZeroOid, NonZeroOid,
-    Repo, SerializedNonZeroOid, SerializedTestResult, TestCommand, WorkingCopyChangesType,
-    TEST_ABORT_EXIT_CODE, TEST_INDETERMINATE_EXIT_CODE, TEST_SUCCESS_EXIT_CODE,
+    Repo, SerializedNonZeroOid, SerializedTestResult, SignOption, TestCommand,
+    WorkingCopyChangesType, TEST_ABORT_EXIT_CODE, TEST_INDETERMINATE_EXIT_CODE,
+    TEST_SUCCESS_EXIT_CODE,
 };
 use lib::try_exit_code;
 use lib::util::{get_sh, ExitCode, EyreExitOr};
@@ -386,6 +387,7 @@ BUG: Expected resolved_interactive ({resolved_interactive:?}) to match interacti
                 resolve_merge_conflicts,
                 dump_rebase_constraints,
                 dump_rebase_plan,
+                sign_options,
             } = move_options;
 
             let force_in_memory = true;
@@ -414,6 +416,7 @@ BUG: Expected resolved_interactive ({resolved_interactive:?}) to match interacti
                     render_smartlog: false,
                     ..Default::default()
                 },
+                sign_option: sign_options.to_owned().into(),
             };
             let permissions =
                 match RebasePlanPermissions::verify_rewrite_set(dag, build_options, commits)? {
@@ -730,6 +733,7 @@ fn set_abort_trap(
                 render_smartlog: false,
                 ..Default::default()
             },
+            sign_option: SignOption::Disable,
         },
     )? {
         ExecuteRebasePlanResult::Succeeded { rewritten_oids: _ } => {
@@ -1969,12 +1973,12 @@ fn apply_fixes(
                 .try_collect()?;
             let fixed_tree = repo.find_tree_or_fail(fixed_tree_oid)?;
             let fixed_commit_oid = repo.create_commit(
-                None,
                 &original_commit.get_author(),
                 &original_commit.get_committer(),
                 commit_message,
                 &fixed_tree,
                 parents.iter().collect(),
+                None,
             )?;
             if original_commit_oid == fixed_commit_oid {
                 continue;
diff --git a/git-branchless/Cargo.toml b/git-branchless/Cargo.toml
index 85fdcf9ee..ad36ad0e2 100644
--- a/git-branchless/Cargo.toml
+++ b/git-branchless/Cargo.toml
@@ -40,6 +40,7 @@ git-branchless-submit = { version = "0.7.0", path = "../git-branchless-submit" }
 git-branchless-test = { version = "0.7.0", path = "../git-branchless-test" }
 git-branchless-undo = { version = "0.7.0", path = "../git-branchless-undo" }
 git-record = { version = "0.3", path = "../git-record" }
+git2-ext = "0.6.0"
 itertools = "0.10.5"
 lazy_static = "1.4.0"
 lib = { package = "git-branchless-lib", version = "0.7.0", path = "../git-branchless-lib" }
diff --git a/git-branchless/src/commands/amend.rs b/git-branchless/src/commands/amend.rs
index 7f97b55cb..6275f6a42 100644
--- a/git-branchless/src/commands/amend.rs
+++ b/git-branchless/src/commands/amend.rs
@@ -26,6 +26,7 @@ use lib::core::rewrite::{
     execute_rebase_plan, move_branches, BuildRebasePlanOptions, ExecuteRebasePlanOptions,
     ExecuteRebasePlanResult, RebasePlanBuilder, RebasePlanPermissions, RepoResource,
 };
+use lib::git::get_signer;
 use lib::git::{AmendFastOptions, GitRunInfo, MaybeZeroOid, Repo, ResolvedReferenceInfo};
 use lib::try_exit_code;
 use lib::util::{ExitCode, EyreExitOr};
@@ -155,12 +156,16 @@ pub fn amend(
         )
     };
 
-    let amended_commit_oid = head_commit.amend_commit(
-        None,
+    let sign_option = move_options.sign_options.to_owned().into();
+    let signer = get_signer(&repo, &sign_option)?;
+
+    let amended_commit_oid = repo.amend_commit(
+        &head_commit,
         Some(&author),
         Some(&committer),
         None,
         Some(&amended_tree),
+        signer.as_deref(),
     )?;
 
     // Switch to the new commit and move any branches. This is kind of a hack:
@@ -265,12 +270,12 @@ pub fn amend(
                     )
                 })?;
                 let reparented_descendant_oid = repo.create_commit(
-                    None,
                     &descendant_commit.get_author(),
                     &descendant_commit.get_committer(),
                     descendant_message,
                     &descendant_commit.get_tree()?,
                     parents.iter().collect(),
+                    signer.as_deref(),
                 )?;
                 builder.replace_commit(descendant_oid, reparented_descendant_oid)?;
             }
@@ -300,6 +305,7 @@ pub fn amend(
                 reset: true,
                 render_smartlog: false,
             },
+            sign_option,
         };
         match execute_rebase_plan(
             effects,
diff --git a/git-branchless/src/commands/mod.rs b/git-branchless/src/commands/mod.rs
index 6629eca83..c41af3988 100644
--- a/git-branchless/src/commands/mod.rs
+++ b/git-branchless/src/commands/mod.rs
@@ -138,6 +138,7 @@ fn command_main(ctx: CommandContext, opts: Opts) -> EyreExitOr<()> {
             force_rewrite_public_commits,
             discard,
             commit_to_fixup,
+            sign_options,
         } => {
             let messages = if discard {
                 git_branchless_reword::InitialCommitMessages::Discard
@@ -153,6 +154,7 @@ fn command_main(ctx: CommandContext, opts: Opts) -> EyreExitOr<()> {
                 messages,
                 &git_run_info,
                 force_rewrite_public_commits,
+                sign_options,
             )?
         }
 
diff --git a/git-branchless/src/commands/restack.rs b/git-branchless/src/commands/restack.rs
index 0b6c72839..802564b1c 100644
--- a/git-branchless/src/commands/restack.rs
+++ b/git-branchless/src/commands/restack.rs
@@ -312,6 +312,7 @@ pub fn restack(
         resolve_merge_conflicts,
         dump_rebase_constraints,
         dump_rebase_plan,
+        ref sign_options,
     } = *move_options;
     let build_options = BuildRebasePlanOptions {
         force_rewrite_public_commits,
@@ -331,6 +332,7 @@ pub fn restack(
             reset: false,
             render_smartlog: false,
         },
+        sign_option: sign_options.to_owned().into(),
     };
     let pool = ThreadPoolBuilder::new().build()?;
     let repo_pool = RepoResource::new_pool(&repo)?;
diff --git a/git-branchless/src/commands/sync.rs b/git-branchless/src/commands/sync.rs
index 280c7719e..c543293c8 100644
--- a/git-branchless/src/commands/sync.rs
+++ b/git-branchless/src/commands/sync.rs
@@ -69,6 +69,7 @@ pub fn sync(
         resolve_merge_conflicts,
         dump_rebase_constraints,
         dump_rebase_plan,
+        ref sign_options,
     } = *move_options;
     let build_options = BuildRebasePlanOptions {
         force_rewrite_public_commits,
@@ -90,6 +91,7 @@ pub fn sync(
             reset: false,
             render_smartlog: false,
         },
+        sign_option: sign_options.to_owned().into(),
     };
     let thread_pool = ThreadPoolBuilder::new().build()?;
     let repo_pool = RepoResource::new_pool(&repo)?;