diff --git a/src/bin/cargo/commands/bench.rs b/src/bin/cargo/commands/bench.rs
index 84681e6bde7..1ce0e5d9855 100644
--- a/src/bin/cargo/commands/bench.rs
+++ b/src/bin/cargo/commands/bench.rs
@@ -82,17 +82,9 @@ pub fn exec(config: &mut Config, args: &ArgMatches<'_>) -> CliResult {
         compile_opts,
     };
 
-    let mut bench_args = vec![];
-    bench_args.extend(
-        args.value_of("BENCHNAME")
-            .into_iter()
-            .map(|s| s.to_string()),
-    );
-    bench_args.extend(
-        args.values_of("args")
-            .unwrap_or_default()
-            .map(|s| s.to_string()),
-    );
+    let bench_args = args.value_of("BENCHNAME").into_iter();
+    let bench_args = bench_args.chain(args.values_of("args").unwrap_or_default());
+    let bench_args = bench_args.collect::<Vec<_>>();
 
     let err = ops::run_benches(&ws, &ops, &bench_args)?;
     match err {
diff --git a/src/bin/cargo/commands/test.rs b/src/bin/cargo/commands/test.rs
index e77aaa547bb..34073e51a38 100644
--- a/src/bin/cargo/commands/test.rs
+++ b/src/bin/cargo/commands/test.rs
@@ -97,13 +97,9 @@ pub fn exec(config: &mut Config, args: &ArgMatches<'_>) -> CliResult {
     // `TESTNAME` is actually an argument of the test binary, but it's
     // important, so we explicitly mention it and reconfigure.
     let test_name: Option<&str> = args.value_of("TESTNAME");
-    let mut test_args = vec![];
-    test_args.extend(test_name.into_iter().map(|s| s.to_string()));
-    test_args.extend(
-        args.values_of("args")
-            .unwrap_or_default()
-            .map(|s| s.to_string()),
-    );
+    let test_args = args.value_of("TESTNAME").into_iter();
+    let test_args = test_args.chain(args.values_of("args").unwrap_or_default());
+    let test_args = test_args.collect::<Vec<_>>();
 
     let no_run = args.is_present("no-run");
     let doc = args.is_present("doc");
diff --git a/src/cargo/ops/cargo_test.rs b/src/cargo/ops/cargo_test.rs
index d335a80a800..daca6ba5939 100644
--- a/src/cargo/ops/cargo_test.rs
+++ b/src/cargo/ops/cargo_test.rs
@@ -15,7 +15,7 @@ pub struct TestOptions<'a> {
 pub fn run_tests(
     ws: &Workspace<'_>,
     options: &TestOptions<'_>,
-    test_args: &[String],
+    test_args: &[&str],
 ) -> CargoResult<Option<CargoTestError>> {
     let compilation = compile_tests(ws, options)?;
 
@@ -42,16 +42,19 @@ pub fn run_tests(
 pub fn run_benches(
     ws: &Workspace<'_>,
     options: &TestOptions<'_>,
-    args: &[String],
+    args: &[&str],
 ) -> CargoResult<Option<CargoTestError>> {
-    let mut args = args.to_vec();
-    args.push("--bench".to_string());
     let compilation = compile_tests(ws, options)?;
 
     if options.no_run {
         return Ok(None);
     }
+
+    let mut args = args.to_vec();
+    args.push("--bench");
+
     let (test, errors) = run_unit_tests(options, &args, &compilation)?;
+
     match errors.len() {
         0 => Ok(None),
         _ => Ok(Some(CargoTestError::new(test, errors))),
@@ -72,7 +75,7 @@ fn compile_tests<'a>(
 /// Runs the unit and integration tests of a package.
 fn run_unit_tests(
     options: &TestOptions<'_>,
-    test_args: &[String],
+    test_args: &[&str],
     compilation: &Compilation<'_>,
 ) -> CargoResult<(Test, Vec<ProcessError>)> {
     let config = options.compile_opts.config;
@@ -125,7 +128,7 @@ fn run_unit_tests(
 
 fn run_doc_tests(
     options: &TestOptions<'_>,
-    test_args: &[String],
+    test_args: &[&str],
     compilation: &Compilation<'_>,
 ) -> CargoResult<(Test, Vec<ProcessError>)> {
     let mut errors = Vec::new();
diff --git a/src/cargo/util/command_prelude.rs b/src/cargo/util/command_prelude.rs
index d004f5561e3..d36f602afb0 100644
--- a/src/cargo/util/command_prelude.rs
+++ b/src/cargo/util/command_prelude.rs
@@ -481,10 +481,7 @@ impl<'a> ArgMatchesExt for ArgMatches<'a> {
 }
 
 pub fn values(args: &ArgMatches<'_>, name: &str) -> Vec<String> {
-    args.values_of(name)
-        .unwrap_or_default()
-        .map(|s| s.to_string())
-        .collect()
+    args._values_of(name)
 }
 
 #[derive(PartialEq, PartialOrd, Eq, Ord)]