diff --git a/compiler/rustc_codegen_ssa/src/back/write.rs b/compiler/rustc_codegen_ssa/src/back/write.rs
index fda8330ea8f11..f72a31d2c236b 100644
--- a/compiler/rustc_codegen_ssa/src/back/write.rs
+++ b/compiler/rustc_codegen_ssa/src/back/write.rs
@@ -118,6 +118,7 @@ pub struct ModuleConfig {
     pub inline_threshold: Option<u32>,
     pub emit_lifetime_markers: bool,
     pub llvm_plugins: Vec<String>,
+    pub autodiff: Vec<String>,
 }
 
 impl ModuleConfig {
@@ -259,6 +260,7 @@ impl ModuleConfig {
             inline_threshold: sess.opts.cg.inline_threshold,
             emit_lifetime_markers: sess.emit_lifetime_markers(),
             llvm_plugins: if_regular!(sess.opts.unstable_opts.llvm_plugins.clone(), vec![]),
+            autodiff: if_regular!(sess.opts.unstable_opts.autodiff.clone(), vec![]),
         }
     }
 
diff --git a/compiler/rustc_interface/src/tests.rs b/compiler/rustc_interface/src/tests.rs
index 04a7714d4137e..6e27eafd63f59 100644
--- a/compiler/rustc_interface/src/tests.rs
+++ b/compiler/rustc_interface/src/tests.rs
@@ -729,6 +729,7 @@ fn test_unstable_options_tracking_hash() {
 
     // Make sure that changing a [TRACKED] option changes the hash.
     // tidy-alphabetical-start
+    tracked!(autodiff, vec![String::from("ad_flags")]);
     tracked!(allow_features, Some(vec![String::from("lang_items")]));
     tracked!(always_encode_mir, true);
     tracked!(asm_comments, true);
diff --git a/compiler/rustc_session/src/config.rs b/compiler/rustc_session/src/config.rs
index 2219fd5e951a8..00afe0a8f8594 100644
--- a/compiler/rustc_session/src/config.rs
+++ b/compiler/rustc_session/src/config.rs
@@ -174,6 +174,32 @@ pub enum InstrumentCoverage {
     Off,
 }
 
+/// The different settings that the `-Z ad` flag can have.
+#[derive(Clone, Copy, PartialEq, Hash, Debug)]
+pub enum AutoDiff {
+    None,
+    PrintTA,
+    PrintAA,
+    PrintPerf,
+    Print,
+    PrintModBefore,
+    PrintModAfterOpts,
+    PrintModAfterEnzyme,
+
+    /// Enzyme's loose type debug helper (can cause incorrect gradients)
+    LooseTypes,
+    /// Output a Module using __enzyme calls to prepare it for opt + enzyme pass usage
+    OPT,
+
+    /// More flags
+    NoModOptAfter,
+    EnableFncOpt,
+    NoVecUnroll,
+    NoSafetyChecks,
+    Inline,
+    AltPipeline,
+}
+
 /// Settings for `-Z instrument-xray` flag.
 #[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Hash)]
 pub struct InstrumentXRay {
@@ -2781,6 +2807,19 @@ pub fn build_session_options(early_dcx: &mut EarlyDiagCtxt, matches: &getopts::M
         }
     }
 
+    // Check for unstable values of -Z ad"
+    //match cg.autodiff {
+    //    AutoDiff::None => {}
+    //    // unstable values
+    //    _ => {
+    //        if !unstable_opts.unstable_options {
+    //            early_dcx.early_fatal(
+    //                "`-Z ad` requires `-Z unstable-options`",
+    //            );
+    //        }
+    //    }
+    //}
+
     if let Ok(graphviz_font) = std::env::var("RUSTC_GRAPHVIZ_FONT") {
         unstable_opts.graphviz_font = graphviz_font;
     }
diff --git a/compiler/rustc_session/src/options.rs b/compiler/rustc_session/src/options.rs
index 10a4bdb94d46f..4d5a032d61be1 100644
--- a/compiler/rustc_session/src/options.rs
+++ b/compiler/rustc_session/src/options.rs
@@ -917,6 +917,42 @@ mod parse {
         }
     }
 
+    //pub(crate) fn parse_autodiff(
+    //    slot: &mut AutoDiff,
+    //    v: Option<&str>,
+    //) -> bool {
+    //    if v.is_none() {
+    //        *slot = AutoDiff::None;
+    //        return true;
+    //    }
+
+    //    let Some(v) = v else {
+    //        *slot = AutoDiff::None;
+    //        return true;
+    //    };
+
+    //    *slot = match v {
+    //        "None" => AutoDiff::None,
+    //        "PrintTA" => AutoDiff::PrintTA,
+    //        "PrintAA" => AutoDiff::PrintAA,
+    //        "PrintPerf" => AutoDiff::PrintPerf,
+    //        "Print" => AutoDiff::Print,
+    //        "PrintModBefore" => AutoDiff::PrintModBefore,
+    //        "PrintModAfterOpts" => AutoDiff::PrintModAfterOpts,
+    //        "PrintModAfterEnzyme" => AutoDiff::PrintModAfterEnzyme,
+    //        "LooseTypes" => AutoDiff::LooseTypes,
+    //        "OPT" => AutoDiff::OPT,
+    //        "NoModOptAfter" => AutoDiff::NoModOptAfter,
+    //        "EnableFncOpt" => AutoDiff::EnableFncOpt,
+    //        "NoVecUnroll" => AutoDiff::NoVecUnroll,
+    //        "NoSafetyChecks" => AutoDiff::NoSafetyChecks,
+    //        "Inline" => AutoDiff::Inline,
+    //        "AltPipeline" => AutoDiff::AltPipeline,
+    //        _ => return false,
+    //    };
+    //    true
+    //}
+
     pub(crate) fn parse_instrument_coverage(
         slot: &mut InstrumentCoverage,
         v: Option<&str>,
@@ -1544,6 +1580,8 @@ options! {
          either `loaded` or `not-loaded`."),
     assume_incomplete_release: bool = (false, parse_bool, [TRACKED],
         "make cfg(version) treat the current version as incomplete (default: no)"),
+    autodiff: Vec<String> = (Vec::new(), parse_list, [TRACKED],
+        "a list autodiff flags to enable (space separated)"),
     #[rustc_lint_opt_deny_field_access("use `Session::binary_dep_depinfo` instead of this field")]
     binary_dep_depinfo: bool = (false, parse_bool, [TRACKED],
         "include artifacts (sysroot, crate dependencies) used during compilation in dep-info \