diff --git a/docs/bot-usage.md b/docs/bot-usage.md
index 84399e87..3a75c917 100644
--- a/docs/bot-usage.md
+++ b/docs/bot-usage.md
@@ -149,6 +149,8 @@ You can specify a toolchain using a rustup name or `branch#sha`, and use the
 following flags:
 * `+rustflags={flags}`: sets the `RUSTFLAGS` environment variable to `{flags}` when
   building with this toolchain, e.g. `+rustflags=-Zverbose`
+* `+cargoflags={flags}`: appends the given `{flags}` to the Cargo command specified
+  by the experiment mode, e.g. `+cargoflags=-Zavoid-dev-deps`
 * `+patch={crate_name}={git_repo_url}={branch}`: patches all crates built by
   this toolchain to resolve the given crate from the given git repository and branch.
 
diff --git a/src/runner/test.rs b/src/runner/test.rs
index 1ac0a24d..17ddcfdb 100644
--- a/src/runner/test.rs
+++ b/src/runner/test.rs
@@ -84,6 +84,11 @@ fn run_cargo<DB: WriteResults>(
     check_errors: bool,
     local_packages_id: &HashSet<PackageId>,
 ) -> Fallible<()> {
+    let mut args = args.to_vec();
+    if let Some(ref tc_cargoflags) = ctx.toolchain.cargoflags {
+        args.extend(tc_cargoflags.split(' '));
+    }
+
     let mut rustflags = format!("--cap-lints={}", ctx.experiment.cap_lints.to_str());
     if let Some(ref tc_rustflags) = ctx.toolchain.rustflags {
         rustflags.push(' ');
@@ -158,7 +163,7 @@ fn run_cargo<DB: WriteResults>(
 
     let mut command = build_env
         .cargo()
-        .args(args)
+        .args(&args)
         .env("CARGO_INCREMENTAL", "0")
         .env("RUST_BACKTRACE", "full")
         .env(rustflags_env, rustflags);
diff --git a/src/server/routes/webhooks/commands.rs b/src/server/routes/webhooks/commands.rs
index 7299c2e3..9f972234 100644
--- a/src/server/routes/webhooks/commands.rs
+++ b/src/server/routes/webhooks/commands.rs
@@ -72,12 +72,14 @@ pub fn run(
             detected_start = Some(Toolchain {
                 source: RustwideToolchain::ci(&build.base_sha, false),
                 rustflags: None,
+                cargoflags: None,
                 ci_try: false,
                 patches: Vec::new(),
             });
             detected_end = Some(Toolchain {
                 source: RustwideToolchain::ci(&build.merge_sha, false),
                 rustflags: None,
+                cargoflags: None,
                 ci_try: true,
                 patches: Vec::new(),
             });
diff --git a/src/toolchain.rs b/src/toolchain.rs
index bc87d6be..093e700c 100644
--- a/src/toolchain.rs
+++ b/src/toolchain.rs
@@ -10,6 +10,7 @@ lazy_static! {
     pub(crate) static ref MAIN_TOOLCHAIN: Toolchain = Toolchain {
         source: RustwideToolchain::dist("stable"),
         rustflags: None,
+        cargoflags: None,
         ci_try: false,
         patches: Vec::new(),
     };
@@ -18,6 +19,7 @@ lazy_static! {
     pub(crate) static ref TEST_TOOLCHAIN: Toolchain = Toolchain {
         source: RustwideToolchain::dist("beta"),
         rustflags: None,
+        cargoflags: None,
         ci_try: false,
         patches: Vec::new(),
     };
@@ -27,6 +29,7 @@ lazy_static! {
 pub struct Toolchain {
     pub source: RustwideToolchain,
     pub rustflags: Option<String>,
+    pub cargoflags: Option<String>,
     pub ci_try: bool,
     pub patches: Vec<CratePatch>,
 }
@@ -65,6 +68,10 @@ impl fmt::Display for Toolchain {
             write!(f, "+rustflags={}", flag)?;
         }
 
+        if let Some(ref flag) = self.cargoflags {
+            write!(f, "+cargoflags={}", flag)?;
+        }
+
         for patch in self.patches.iter() {
             write!(f, "+patch={}", patch)?;
         }
@@ -114,6 +121,7 @@ impl FromStr for Toolchain {
         };
 
         let mut rustflags = None;
+        let mut cargoflags = None;
         let mut patches: Vec<CratePatch> = vec![];
         for part in parts {
             if let Some(equal_idx) = part.find('=') {
@@ -126,6 +134,7 @@ impl FromStr for Toolchain {
 
                 match flag {
                     "rustflags" => rustflags = Some(value),
+                    "cargoflags" => cargoflags = Some(value),
                     "patch" => patches.push(value.parse()?),
                     unknown => return Err(ToolchainParseError::InvalidFlag(unknown.to_string())),
                 }
@@ -137,6 +146,7 @@ impl FromStr for Toolchain {
         Ok(Toolchain {
             source,
             rustflags,
+            cargoflags,
             ci_try,
             patches,
         })
@@ -189,14 +199,25 @@ mod tests {
                     test_from_str!($str => Toolchain {
                         source: $source,
                         rustflags: None,
+                        cargoflags: None,
                         ci_try: $ci_try,
                         patches: Vec::new(),
                     });
 
-                    // Test parsing with flags
+                    // Test parsing with rustflags
                     test_from_str!(concat!($str, "+rustflags=foo bar") => Toolchain {
                         source: $source,
                         rustflags: Some("foo bar".to_string()),
+                        cargoflags: None,
+                        ci_try: $ci_try,
+                        patches: Vec::new(),
+                    });
+
+                    // Test parsing with cargoflags
+                    test_from_str!(concat!($str, "+cargoflags=foo bar") => Toolchain {
+                        source: $source,
+                        rustflags: None,
+                        cargoflags: Some("foo bar".to_string()),
                         ci_try: $ci_try,
                         patches: Vec::new(),
                     });
@@ -205,6 +226,7 @@ mod tests {
                     test_from_str!(concat!($str, "+patch=example=https://git.example.com/some/repo=master") => Toolchain {
                         source: $source,
                         rustflags: None,
+                        cargoflags: None,
                         ci_try: $ci_try,
                         patches: vec![CratePatch {
                             name: "example".to_string(),
@@ -217,6 +239,7 @@ mod tests {
                     test_from_str!(concat!($str, "+rustflags=foo bar+patch=example=https://git.example.com/some/repo=master") => Toolchain {
                         source: $source,
                         rustflags: Some("foo bar".to_string()),
+                        cargoflags: None,
                         ci_try: $ci_try,
                         patches: vec![CratePatch {
                             name: "example".to_string(),