diff --git a/Cargo.toml b/Cargo.toml
index b234f2861a0..918d83dbe25 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -103,6 +103,7 @@ features = [
 
 [dev-dependencies]
 cargo-test-macro = { path = "crates/cargo-test-macro", version = "0.1.0" }
+cargo-test-support = { path = "crates/cargo-test-support", version = "0.1.0" }
 
 [[bin]]
 name = "cargo"
diff --git a/azure-pipelines.yml b/azure-pipelines.yml
index 5bb3f65094f..503ef785266 100644
--- a/azure-pipelines.yml
+++ b/azure-pipelines.yml
@@ -43,6 +43,7 @@ jobs:
       x86_64-msvc:
         TOOLCHAIN: stable-x86_64-pc-windows-msvc
         OTHER_TARGET: i686-pc-windows-msvc
+
 - job: rustfmt
   pool:
     vmImage: ubuntu-16.04
@@ -54,6 +55,8 @@ jobs:
       displayName: "Check rustfmt (cargo)"
     - bash: cd crates/cargo-test-macro && cargo fmt --all -- --check
       displayName: "Check rustfmt (cargo-test-macro)"
+    - bash: cd crates/cargo-test-support && cargo fmt --all -- --check
+      displayName: "Check rustfmt (cargo-test-support)"
     - bash: cd crates/crates-io && cargo fmt --all -- --check
       displayName: "Check rustfmt (crates-io)"
     - bash: cd crates/resolver-tests && cargo fmt --all -- --check
@@ -71,6 +74,20 @@ jobs:
   variables:
     TOOLCHAIN: stable
 
+- job: build_std
+  pool:
+    vmImage: ubuntu-16.04
+  steps:
+    - template: ci/azure-install-rust.yml
+    - bash: rustup component add rust-src
+      displayName: "Install rust-src"
+    - bash: cargo build
+    - bash: cargo test --test build-std
+      displayName: "tests"
+  variables:
+    TOOLCHAIN: nightly
+    CARGO_RUN_BUILD_STD_TESTS: 1
+
 - job: docs
   pool:
     vmImage: ubuntu-16.04
@@ -88,4 +105,3 @@ jobs:
       displayName: "Build mdbook documentation"
   variables:
     TOOLCHAIN: stable
-
diff --git a/ci/azure-test-all.yml b/ci/azure-test-all.yml
index ad6c2fed59d..4b4cc9c2134 100644
--- a/ci/azure-test-all.yml
+++ b/ci/azure-test-all.yml
@@ -16,11 +16,6 @@ steps:
 - bash: rustup component add clippy || echo "clippy not available"
   displayName: "Install clippy (maybe)"
 
-# This is needed for standard library tests.
-- bash: rustup component add rust-src
-  condition: and(succeeded(), eq(variables['TOOLCHAIN'], 'nightly'))
-  displayName: "Install rust-src (maybe)"
-
 # Deny warnings on CI to avoid warnings getting into the codebase, and note the
 # `force-system-lib-on-osx` which is intended to fix compile issues on OSX where
 # compiling curl from source on OSX yields linker errors on Azure.
@@ -31,3 +26,6 @@ steps:
 # fix the link errors.
 - bash: cargo test --features 'deny-warnings curl/force-system-lib-on-osx'
   displayName: "cargo test"
+
+- bash: cargo test -p cargo-test-support
+  displayName: "cargo test -p cargo-test-support"
diff --git a/crates/cargo-test-macro/src/lib.rs b/crates/cargo-test-macro/src/lib.rs
index 678bb83c0cb..b16915762a4 100644
--- a/crates/cargo-test-macro/src/lib.rs
+++ b/crates/cargo-test-macro/src/lib.rs
@@ -3,7 +3,7 @@ extern crate proc_macro;
 use proc_macro::*;
 
 #[proc_macro_attribute]
-pub fn cargo_test(_attr: TokenStream, item: TokenStream) -> TokenStream {
+pub fn cargo_test(attr: TokenStream, item: TokenStream) -> TokenStream {
     let span = Span::call_site();
     let mut ret = TokenStream::new();
     ret.extend(Some(TokenTree::from(Punct::new('#', Spacing::Alone))));
@@ -13,6 +13,8 @@ pub fn cargo_test(_attr: TokenStream, item: TokenStream) -> TokenStream {
         test.into(),
     ))));
 
+    let build_std = contains_ident(&attr, "build_std");
+
     for token in item {
         let group = match token {
             TokenTree::Group(g) => {
@@ -29,25 +31,20 @@ pub fn cargo_test(_attr: TokenStream, item: TokenStream) -> TokenStream {
             }
         };
 
-        let mut new_body = vec![
-            TokenTree::from(Ident::new("let", span)),
-            TokenTree::from(Ident::new("_test_guard", span)),
-            TokenTree::from(Punct::new('=', Spacing::Alone)),
-            TokenTree::from(Ident::new("crate", span)),
-            TokenTree::from(Punct::new(':', Spacing::Joint)),
-            TokenTree::from(Punct::new(':', Spacing::Alone)),
-            TokenTree::from(Ident::new("support", span)),
-            TokenTree::from(Punct::new(':', Spacing::Joint)),
-            TokenTree::from(Punct::new(':', Spacing::Alone)),
-            TokenTree::from(Ident::new("paths", span)),
-            TokenTree::from(Punct::new(':', Spacing::Joint)),
-            TokenTree::from(Punct::new(':', Spacing::Alone)),
-            TokenTree::from(Ident::new("init_root", span)),
-            TokenTree::from(Group::new(Delimiter::Parenthesis, TokenStream::new())),
-            TokenTree::from(Punct::new(';', Spacing::Alone)),
-        ]
-        .into_iter()
-        .collect::<TokenStream>();
+        let mut new_body =
+            to_token_stream("let _test_guard = cargo_test_support::paths::init_root();");
+
+        // If this is a `build_std` test (aka `tests/build-std/*.rs`) then they
+        // only run on nightly and they only run when specifically instructed to
+        // on CI.
+        if build_std {
+            let ts = to_token_stream("if !cargo_test_support::is_nightly() { return }");
+            new_body.extend(ts);
+            let ts = to_token_stream(
+                "if std::env::var(\"CARGO_RUN_BUILD_STD_TESTS\").is_err() { return }",
+            );
+            new_body.extend(ts);
+        }
         new_body.extend(group.stream());
         ret.extend(Some(TokenTree::from(Group::new(
             group.delimiter(),
@@ -57,3 +54,14 @@ pub fn cargo_test(_attr: TokenStream, item: TokenStream) -> TokenStream {
 
     return ret;
 }
+
+fn contains_ident(t: &TokenStream, ident: &str) -> bool {
+    t.clone().into_iter().any(|t| match t {
+        TokenTree::Ident(i) => i.to_string() == ident,
+        _ => false,
+    })
+}
+
+fn to_token_stream(code: &str) -> TokenStream {
+    code.parse().unwrap()
+}
diff --git a/crates/cargo-test-support/Cargo.toml b/crates/cargo-test-support/Cargo.toml
new file mode 100644
index 00000000000..bf9983dc207
--- /dev/null
+++ b/crates/cargo-test-support/Cargo.toml
@@ -0,0 +1,21 @@
+[package]
+name = "cargo-test-support"
+version = "0.1.0"
+authors = ["Alex Crichton <alex@alexcrichton.com>"]
+edition = "2018"
+
+[lib]
+doctest = false
+
+[dependencies]
+cargo = { path = "../.." }
+cargo-test-macro = { path = "../cargo-test-macro" }
+filetime = "0.2"
+flate2 = "1.0"
+git2 = "0.10"
+glob = "0.3"
+lazy_static = "1.0"
+remove_dir_all = "0.5"
+serde_json = "1.0"
+tar = "0.4"
+url = "2.0"
diff --git a/tests/testsuite/support/cross_compile.rs b/crates/cargo-test-support/src/cross_compile.rs
similarity index 98%
rename from tests/testsuite/support/cross_compile.rs
rename to crates/cargo-test-support/src/cross_compile.rs
index ac072822dba..ce3d0444251 100644
--- a/tests/testsuite/support/cross_compile.rs
+++ b/crates/cargo-test-support/src/cross_compile.rs
@@ -1,10 +1,9 @@
+use crate::{basic_bin_manifest, main_file, project};
 use std::env;
 use std::process::Command;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::Once;
 
-use crate::support::{basic_bin_manifest, main_file, project};
-
 pub fn disabled() -> bool {
     // First, disable if `./configure` requested so.
     match env::var("CFG_DISABLE_CROSS_TESTS") {
diff --git a/tests/testsuite/support/git.rs b/crates/cargo-test-support/src/git.rs
similarity index 98%
rename from tests/testsuite/support/git.rs
rename to crates/cargo-test-support/src/git.rs
index 1213594c2cd..d9184061e08 100644
--- a/tests/testsuite/support/git.rs
+++ b/crates/cargo-test-support/src/git.rs
@@ -38,15 +38,13 @@ use some of the helper functions in this file to interact with the repository.
 
 */
 
+use crate::{path2url, project, Project, ProjectBuilder};
+use git2;
 use std::fs::{self, File};
 use std::io::prelude::*;
 use std::path::{Path, PathBuf};
-
-use git2;
 use url::Url;
 
-use crate::support::{path2url, project, Project, ProjectBuilder};
-
 #[must_use]
 pub struct RepoBuilder {
     repo: git2::Repository,
diff --git a/tests/testsuite/support/install.rs b/crates/cargo-test-support/src/install.rs
similarity index 96%
rename from tests/testsuite/support/install.rs
rename to crates/cargo-test-support/src/install.rs
index 8e5bbd073bc..bd228bf345c 100644
--- a/tests/testsuite/support/install.rs
+++ b/crates/cargo-test-support/src/install.rs
@@ -1,8 +1,7 @@
+use crate::paths;
 use std::env::consts::EXE_SUFFIX;
 use std::path::{Path, PathBuf};
 
-use crate::support::paths;
-
 /// Used by `cargo install` tests to assert an executable binary
 /// has been installed. Example usage:
 ///
diff --git a/tests/testsuite/support/mod.rs b/crates/cargo-test-support/src/lib.rs
similarity index 99%
rename from tests/testsuite/support/mod.rs
rename to crates/cargo-test-support/src/lib.rs
index 063f82fae10..2ceb6bf6526 100644
--- a/tests/testsuite/support/mod.rs
+++ b/crates/cargo-test-support/src/lib.rs
@@ -125,6 +125,7 @@ use url::Url;
 
 use self::paths::CargoPathExt;
 
+#[macro_export]
 macro_rules! t {
     ($e:expr) => {
         match $e {
@@ -134,6 +135,8 @@ macro_rules! t {
     };
 }
 
+pub use cargo_test_macro::cargo_test;
+
 pub mod cross_compile;
 pub mod git;
 pub mod paths;
@@ -409,7 +412,7 @@ impl Project {
     ///             .with_stdout("bar\n")
     ///             .run();
     pub fn process<T: AsRef<OsStr>>(&self, program: T) -> Execs {
-        let mut p = crate::support::process(program);
+        let mut p = process(program);
         p.cwd(self.root());
         execs().with_process_builder(p)
     }
@@ -1425,7 +1428,7 @@ pub fn lines_match(expected: &str, mut actual: &str) -> bool {
     actual.is_empty() || expected.ends_with("[..]")
 }
 
-#[cargo_test]
+#[test]
 fn lines_match_works() {
     assert!(lines_match("a b", "a b"));
     assert!(lines_match("a[..]b", "a b"));
diff --git a/tests/testsuite/support/paths.rs b/crates/cargo-test-support/src/paths.rs
similarity index 99%
rename from tests/testsuite/support/paths.rs
rename to crates/cargo-test-support/src/paths.rs
index bf3c763de87..6b3af85c6d1 100644
--- a/tests/testsuite/support/paths.rs
+++ b/crates/cargo-test-support/src/paths.rs
@@ -1,3 +1,5 @@
+use filetime::{self, FileTime};
+use lazy_static::lazy_static;
 use std::cell::RefCell;
 use std::collections::HashMap;
 use std::env;
@@ -7,9 +9,6 @@ use std::path::{Path, PathBuf};
 use std::sync::atomic::{AtomicUsize, Ordering};
 use std::sync::Mutex;
 
-use filetime::{self, FileTime};
-use lazy_static::lazy_static;
-
 static CARGO_INTEGRATION_TEST_DIR: &str = "cit";
 
 lazy_static! {
diff --git a/tests/testsuite/support/publish.rs b/crates/cargo-test-support/src/publish.rs
similarity index 98%
rename from tests/testsuite/support/publish.rs
rename to crates/cargo-test-support/src/publish.rs
index 545007515db..36afd91a150 100644
--- a/tests/testsuite/support/publish.rs
+++ b/crates/cargo-test-support/src/publish.rs
@@ -1,12 +1,10 @@
+use crate::registry::{self, alt_api_path};
+use crate::{find_json_mismatch, lines_match};
+use flate2::read::GzDecoder;
 use std::collections::{HashMap, HashSet};
 use std::fs::File;
 use std::io::{self, prelude::*, SeekFrom};
 use std::path::{Path, PathBuf};
-
-use crate::support::registry::{self, alt_api_path};
-use crate::support::{find_json_mismatch, lines_match};
-
-use flate2::read::GzDecoder;
 use tar::Archive;
 
 fn read_le_u32<R>(mut reader: R) -> io::Result<u32>
diff --git a/tests/testsuite/support/registry.rs b/crates/cargo-test-support/src/registry.rs
similarity index 99%
rename from tests/testsuite/support/registry.rs
rename to crates/cargo-test-support/src/registry.rs
index 709f748ce6a..88b24672f99 100644
--- a/tests/testsuite/support/registry.rs
+++ b/crates/cargo-test-support/src/registry.rs
@@ -1,18 +1,16 @@
-use std::collections::HashMap;
-use std::fs::{self, File};
-use std::io::prelude::*;
-use std::path::{Path, PathBuf};
-
+use crate::git::repo;
+use crate::paths;
 use cargo::sources::CRATES_IO_INDEX;
 use cargo::util::Sha256;
 use flate2::write::GzEncoder;
 use flate2::Compression;
+use std::collections::HashMap;
+use std::fs::{self, File};
+use std::io::prelude::*;
+use std::path::{Path, PathBuf};
 use tar::{Builder, Header};
 use url::Url;
 
-use crate::support::git::repo;
-use crate::support::paths;
-
 /// Gets the path to the local index pretending to be crates.io. This is a Git repo
 /// initialized with a `config.json` file pointing to `dl_path` for downloads
 /// and `api_path` for uploads.
diff --git a/src/cargo/core/compiler/standard_lib.rs b/src/cargo/core/compiler/standard_lib.rs
index fb58363f0d5..a6fced9cc1b 100644
--- a/src/cargo/core/compiler/standard_lib.rs
+++ b/src/cargo/core/compiler/standard_lib.rs
@@ -7,6 +7,7 @@ use crate::core::{Dependency, PackageId, PackageSet, Resolve, SourceId, Workspac
 use crate::ops::{self, Packages};
 use crate::util::errors::CargoResult;
 use std::collections::{HashMap, HashSet};
+use std::env;
 use std::path::PathBuf;
 
 /// Parse the `-Zbuild-std` flag.
@@ -148,6 +149,10 @@ pub fn generate_std_roots<'a>(
 }
 
 fn detect_sysroot_src_path(ws: &Workspace<'_>) -> CargoResult<PathBuf> {
+    if let Some(s) = env::var_os("__CARGO_TESTS_ONLY_SRC_ROOT") {
+        return Ok(s.into());
+    }
+
     // NOTE: This is temporary until we figure out how to acquire the source.
     // If we decide to keep the sysroot probe, then BuildConfig will need to
     // be restructured so that the TargetInfo is created earlier and passed
diff --git a/tests/build-std/main.rs b/tests/build-std/main.rs
new file mode 100644
index 00000000000..6e2dbc03019
--- /dev/null
+++ b/tests/build-std/main.rs
@@ -0,0 +1,180 @@
+//! A test suite for `-Zbuild-std` which is much more expensive than the
+//! standard test suite.
+//!
+//! This test suite attempts to perform a full integration test where we
+//! actually compile the standard library from source (like the real one) and
+//! the various tests associated with that.
+//!
+//! YOU SHOULD IDEALLY NOT WRITE TESTS HERE.
+//!
+//! If possible, use `tests/testsuite/standard_lib.rs` instead. That uses a
+//! 'mock' sysroot which is much faster to compile. The tests here are
+//! extremely intensive and are only intended to run on CI and are theoretically
+//! not catching any regressions that `tests/testsuite/standard_lib.rs` isn't
+//! already catching.
+//!
+//! All tests here should use `#[cargo_test(build_std)]` to indicate that
+//! boilerplate should be generated to require the nightly toolchain and the
+//! `CARGO_RUN_BUILD_STD_TESTS` env var to be set to actually run these tests.
+//! Otherwise the tests are skipped.
+
+use cargo_test_support::*;
+
+fn enable_build_std(e: &mut Execs, arg: Option<&str>) {
+    e.env_remove("CARGO_HOME");
+    e.env_remove("HOME");
+    e.arg("-Zno-index-update");
+
+    // And finally actually enable `build-std` for now
+    let arg = match arg {
+        Some(s) => format!("-Zbuild-std={}", s),
+        None => "-Zbuild-std".to_string(),
+    };
+    e.arg(arg);
+    e.masquerade_as_nightly_cargo();
+}
+
+// Helper methods used in the tests below
+trait BuildStd: Sized {
+    fn build_std(&mut self) -> &mut Self;
+    fn build_std_arg(&mut self, arg: &str) -> &mut Self;
+    fn target_host(&mut self) -> &mut Self;
+}
+
+impl BuildStd for Execs {
+    fn build_std(&mut self) -> &mut Self {
+        enable_build_std(self, None);
+        self
+    }
+
+    fn build_std_arg(&mut self, arg: &str) -> &mut Self {
+        enable_build_std(self, Some(arg));
+        self
+    }
+
+    fn target_host(&mut self) -> &mut Self {
+        self.arg("--target").arg(rustc_host());
+        self
+    }
+}
+
+#[cargo_test(build_std)]
+fn basic() {
+    let p = project()
+        .file(
+            "src/main.rs",
+            "
+                fn main() {
+                    foo::f();
+                }
+
+                #[test]
+                fn smoke_bin_unit() {
+                    foo::f();
+                }
+            ",
+        )
+        .file(
+            "src/lib.rs",
+            "
+                extern crate alloc;
+                extern crate proc_macro;
+
+                /// ```
+                /// foo::f();
+                /// ```
+                pub fn f() {
+                }
+
+                #[test]
+                fn smoke_lib_unit() {
+                    f();
+                }
+            ",
+        )
+        .file(
+            "tests/smoke.rs",
+            "
+                #[test]
+                fn smoke_integration() {
+                    foo::f();
+                }
+            ",
+        )
+        .build();
+
+    p.cargo("check").build_std().target_host().run();
+    p.cargo("build").build_std().target_host().run();
+    p.cargo("run").build_std().target_host().run();
+    p.cargo("test").build_std().target_host().run();
+}
+
+#[cargo_test(build_std)]
+fn cross_custom() {
+    let p = project()
+        .file("src/lib.rs", "#![no_std] pub fn f() {}")
+        .file(
+            "custom-target.json",
+            r#"
+            {
+                "llvm-target": "x86_64-unknown-none-gnu",
+                "data-layout": "e-m:e-i64:64-f80:128-n8:16:32:64-S128",
+                "arch": "x86_64",
+                "target-endian": "little",
+                "target-pointer-width": "64",
+                "target-c-int-width": "32",
+                "os": "none",
+                "linker-flavor": "ld.lld"
+            }
+            "#,
+        )
+        .build();
+
+    p.cargo("build --target custom-target.json -v")
+        .build_std_arg("core")
+        .run();
+}
+
+#[cargo_test(build_std)]
+fn custom_test_framework() {
+    let p = project()
+        .file(
+            "src/lib.rs",
+            r#"
+            #![no_std]
+            #![cfg_attr(test, no_main)]
+            #![feature(custom_test_frameworks)]
+            #![test_runner(crate::test_runner)]
+
+            pub fn test_runner(_tests: &[&dyn Fn()]) {}
+
+            #[panic_handler]
+            fn panic(_info: &core::panic::PanicInfo) -> ! {
+                loop {}
+            }
+            "#,
+        )
+        .file(
+            "target.json",
+            r#"
+            {
+                "llvm-target": "x86_64-unknown-none-gnu",
+                "data-layout": "e-m:e-i64:64-f80:128-n8:16:32:64-S128",
+                "arch": "x86_64",
+                "target-endian": "little",
+                "target-pointer-width": "64",
+                "target-c-int-width": "32",
+                "os": "none",
+                "linker-flavor": "ld.lld",
+                "linker": "rust-lld",
+                "executables": true,
+                "panic-strategy": "abort"
+            }
+            "#,
+        )
+        .build();
+
+    p.cargo("test --target target.json --no-run -v")
+        .build_std_arg("core")
+        .run();
+}
diff --git a/tests/testsuite/alt_registry.rs b/tests/testsuite/alt_registry.rs
index fd5729e6073..6441ab0a8c4 100644
--- a/tests/testsuite/alt_registry.rs
+++ b/tests/testsuite/alt_registry.rs
@@ -1,7 +1,7 @@
-use crate::support::publish::validate_alt_upload;
-use crate::support::registry::{self, Package};
-use crate::support::{basic_manifest, git, paths, project};
 use cargo::util::IntoUrl;
+use cargo_test_support::publish::validate_alt_upload;
+use cargo_test_support::registry::{self, Package};
+use cargo_test_support::{basic_manifest, git, paths, project};
 use std::fs::{self, File};
 use std::io::Write;
 
diff --git a/tests/testsuite/bad_config.rs b/tests/testsuite/bad_config.rs
index cab90956d83..e932b68a353 100644
--- a/tests/testsuite/bad_config.rs
+++ b/tests/testsuite/bad_config.rs
@@ -1,5 +1,5 @@
-use crate::support::registry::Package;
-use crate::support::{basic_manifest, project};
+use cargo_test_support::registry::Package;
+use cargo_test_support::{basic_manifest, project};
 
 #[cargo_test]
 fn bad1() {
diff --git a/tests/testsuite/bad_manifest_path.rs b/tests/testsuite/bad_manifest_path.rs
index 83990a5a7be..8e54f5f641b 100644
--- a/tests/testsuite/bad_manifest_path.rs
+++ b/tests/testsuite/bad_manifest_path.rs
@@ -1,4 +1,4 @@
-use crate::support::{basic_bin_manifest, main_file, project};
+use cargo_test_support::{basic_bin_manifest, main_file, project};
 
 fn assert_not_a_cargo_toml(command: &str, manifest_path_argument: &str) {
     let p = project()
diff --git a/tests/testsuite/bench.rs b/tests/testsuite/bench.rs
index 0e8c78543fd..17574dc91f9 100644
--- a/tests/testsuite/bench.rs
+++ b/tests/testsuite/bench.rs
@@ -1,6 +1,6 @@
-use crate::support::is_nightly;
-use crate::support::paths::CargoPathExt;
-use crate::support::{basic_bin_manifest, basic_lib_manifest, basic_manifest, project};
+use cargo_test_support::is_nightly;
+use cargo_test_support::paths::CargoPathExt;
+use cargo_test_support::{basic_bin_manifest, basic_lib_manifest, basic_manifest, project};
 
 #[cargo_test]
 fn cargo_bench_simple() {
diff --git a/tests/testsuite/build.rs b/tests/testsuite/build.rs
index 016eaac8d5a..7e8708a27ec 100644
--- a/tests/testsuite/build.rs
+++ b/tests/testsuite/build.rs
@@ -1,15 +1,14 @@
+use cargo::util::paths::dylib_path_envvar;
+use cargo_test_support::paths::{root, CargoPathExt};
+use cargo_test_support::registry::Package;
+use cargo_test_support::{
+    basic_bin_manifest, basic_lib_manifest, basic_manifest, main_file, project, rustc_host,
+    sleep_ms, symlink_supported, t, Execs, ProjectBuilder,
+};
 use std::env;
 use std::fs::{self, File};
 use std::io::prelude::*;
 
-use crate::support::paths::{root, CargoPathExt};
-use crate::support::registry::Package;
-use crate::support::{
-    basic_bin_manifest, basic_lib_manifest, basic_manifest, main_file, project, rustc_host,
-    sleep_ms, symlink_supported, Execs, ProjectBuilder,
-};
-use cargo::util::paths::dylib_path_envvar;
-
 #[cargo_test]
 fn cargo_compile_simple() {
     let p = project()
@@ -4541,7 +4540,7 @@ Caused by:
 
 #[cargo_test]
 fn tricky_pipelining() {
-    if !crate::support::is_nightly() {
+    if !cargo_test_support::is_nightly() {
         return;
     }
 
@@ -4571,7 +4570,7 @@ fn tricky_pipelining() {
 
 #[cargo_test]
 fn pipelining_works() {
-    if !crate::support::is_nightly() {
+    if !cargo_test_support::is_nightly() {
         return;
     }
 
@@ -4606,7 +4605,7 @@ fn pipelining_works() {
 
 #[cargo_test]
 fn pipelining_big_graph() {
-    if !crate::support::is_nightly() {
+    if !cargo_test_support::is_nightly() {
         return;
     }
 
diff --git a/tests/testsuite/build_auth.rs b/tests/testsuite/build_auth.rs
index 2509f90a32f..d76f93e90b6 100644
--- a/tests/testsuite/build_auth.rs
+++ b/tests/testsuite/build_auth.rs
@@ -6,8 +6,8 @@ use std::sync::atomic::{AtomicUsize, Ordering::SeqCst};
 use std::sync::Arc;
 use std::thread;
 
-use crate::support::paths;
-use crate::support::{basic_manifest, project};
+use cargo_test_support::paths;
+use cargo_test_support::{basic_manifest, project};
 use git2;
 
 // Tests that HTTP auth is offered from `credential.helper`.
diff --git a/tests/testsuite/build_lib.rs b/tests/testsuite/build_lib.rs
index f93187d535d..2e4d181248d 100644
--- a/tests/testsuite/build_lib.rs
+++ b/tests/testsuite/build_lib.rs
@@ -1,4 +1,4 @@
-use crate::support::{basic_bin_manifest, basic_manifest, project};
+use cargo_test_support::{basic_bin_manifest, basic_manifest, project};
 
 #[cargo_test]
 fn build_lib_only() {
diff --git a/tests/testsuite/build_plan.rs b/tests/testsuite/build_plan.rs
index f23078e4ba3..3874986c245 100644
--- a/tests/testsuite/build_plan.rs
+++ b/tests/testsuite/build_plan.rs
@@ -1,5 +1,5 @@
-use crate::support::registry::Package;
-use crate::support::{basic_bin_manifest, basic_manifest, main_file, project};
+use cargo_test_support::registry::Package;
+use cargo_test_support::{basic_bin_manifest, basic_manifest, main_file, project};
 
 #[cargo_test]
 fn cargo_build_plan_simple() {
diff --git a/tests/testsuite/build_script.rs b/tests/testsuite/build_script.rs
index c4f39f3ff7a..a3a13caf81c 100644
--- a/tests/testsuite/build_script.rs
+++ b/tests/testsuite/build_script.rs
@@ -4,11 +4,11 @@ use std::io;
 use std::io::prelude::*;
 use std::thread;
 
-use crate::support::paths::CargoPathExt;
-use crate::support::registry::Package;
-use crate::support::{basic_manifest, cross_compile, project};
-use crate::support::{rustc_host, sleep_ms, slow_cpu_multiplier};
 use cargo::util::paths::remove_dir_all;
+use cargo_test_support::paths::CargoPathExt;
+use cargo_test_support::registry::Package;
+use cargo_test_support::{basic_manifest, cross_compile, project};
+use cargo_test_support::{rustc_host, sleep_ms, slow_cpu_multiplier};
 
 #[cargo_test]
 fn custom_build_script_failed() {
@@ -2277,7 +2277,7 @@ fn flags_go_into_tests() {
 #[cargo_test]
 fn diamond_passes_args_only_once() {
     // FIXME: when pipelining rides to stable, enable this test on all channels.
-    if !crate::support::is_nightly() {
+    if !cargo_test_support::is_nightly() {
         return;
     }
 
diff --git a/tests/testsuite/build_script_env.rs b/tests/testsuite/build_script_env.rs
index 5b2a5795b66..f45a430d6cc 100644
--- a/tests/testsuite/build_script_env.rs
+++ b/tests/testsuite/build_script_env.rs
@@ -1,7 +1,7 @@
 use std::fs::File;
 
-use crate::support::project;
-use crate::support::sleep_ms;
+use cargo_test_support::project;
+use cargo_test_support::sleep_ms;
 
 #[cargo_test]
 fn rerun_if_env_changes() {
diff --git a/tests/testsuite/cache_messages.rs b/tests/testsuite/cache_messages.rs
index 2582d191810..7a104e959f3 100644
--- a/tests/testsuite/cache_messages.rs
+++ b/tests/testsuite/cache_messages.rs
@@ -1,4 +1,4 @@
-use crate::support::{clippy_is_available, is_nightly, process, project, registry::Package};
+use cargo_test_support::{clippy_is_available, is_nightly, process, project, registry::Package};
 use std::path::Path;
 
 fn as_str(bytes: &[u8]) -> &str {
diff --git a/tests/testsuite/cargo_alias_config.rs b/tests/testsuite/cargo_alias_config.rs
index 3d0e14c127c..8ce0f51adfe 100644
--- a/tests/testsuite/cargo_alias_config.rs
+++ b/tests/testsuite/cargo_alias_config.rs
@@ -1,4 +1,4 @@
-use crate::support::{basic_bin_manifest, project};
+use cargo_test_support::{basic_bin_manifest, project};
 
 #[cargo_test]
 fn alias_incorrect_config_type() {
diff --git a/tests/testsuite/cargo_command.rs b/tests/testsuite/cargo_command.rs
index dbc53bf0631..e0f4cda2e6b 100644
--- a/tests/testsuite/cargo_command.rs
+++ b/tests/testsuite/cargo_command.rs
@@ -4,11 +4,11 @@ use std::io::prelude::*;
 use std::path::{Path, PathBuf};
 use std::str;
 
-use crate::support::cargo_process;
-use crate::support::paths::{self, CargoPathExt};
-use crate::support::registry::Package;
-use crate::support::{basic_bin_manifest, basic_manifest, cargo_exe, project, Project};
 use cargo;
+use cargo_test_support::cargo_process;
+use cargo_test_support::paths::{self, CargoPathExt};
+use cargo_test_support::registry::Package;
+use cargo_test_support::{basic_bin_manifest, basic_manifest, cargo_exe, project, Project};
 
 #[cfg_attr(windows, allow(dead_code))]
 enum FakeKind<'a> {
diff --git a/tests/testsuite/cargo_features.rs b/tests/testsuite/cargo_features.rs
index 0dd4af06aa6..45524d1c7e1 100644
--- a/tests/testsuite/cargo_features.rs
+++ b/tests/testsuite/cargo_features.rs
@@ -1,4 +1,4 @@
-use crate::support::{project, registry};
+use cargo_test_support::{project, registry};
 
 #[cargo_test]
 fn feature_required() {
diff --git a/tests/testsuite/cfg.rs b/tests/testsuite/cfg.rs
index 81eab7e7b6e..abba59e3523 100644
--- a/tests/testsuite/cfg.rs
+++ b/tests/testsuite/cfg.rs
@@ -1,10 +1,10 @@
 use std::fmt;
 use std::str::FromStr;
 
-use crate::support::registry::Package;
-use crate::support::rustc_host;
-use crate::support::{basic_manifest, project};
 use cargo::util::{Cfg, CfgExpr};
+use cargo_test_support::registry::Package;
+use cargo_test_support::rustc_host;
+use cargo_test_support::{basic_manifest, project};
 
 macro_rules! c {
     ($a:ident) => {
diff --git a/tests/testsuite/check.rs b/tests/testsuite/check.rs
index 8fc886a88a4..a4eab3b2229 100644
--- a/tests/testsuite/check.rs
+++ b/tests/testsuite/check.rs
@@ -1,9 +1,9 @@
 use std::fmt::{self, Write};
 
-use crate::support::install::exe;
-use crate::support::paths::CargoPathExt;
-use crate::support::registry::Package;
-use crate::support::{basic_manifest, project};
+use cargo_test_support::install::exe;
+use cargo_test_support::paths::CargoPathExt;
+use cargo_test_support::registry::Package;
+use cargo_test_support::{basic_manifest, project};
 
 #[cargo_test]
 fn check_success() {
diff --git a/tests/testsuite/clean.rs b/tests/testsuite/clean.rs
index c3ee4c7becc..103b707f1e5 100644
--- a/tests/testsuite/clean.rs
+++ b/tests/testsuite/clean.rs
@@ -1,7 +1,7 @@
 use std::env;
 
-use crate::support::registry::Package;
-use crate::support::{basic_bin_manifest, basic_manifest, git, main_file, project};
+use cargo_test_support::registry::Package;
+use cargo_test_support::{basic_bin_manifest, basic_manifest, git, main_file, project};
 
 #[cargo_test]
 fn cargo_clean_simple() {
diff --git a/tests/testsuite/clippy.rs b/tests/testsuite/clippy.rs
index 271f6878a02..5e5000ff83f 100644
--- a/tests/testsuite/clippy.rs
+++ b/tests/testsuite/clippy.rs
@@ -1,4 +1,4 @@
-use crate::support::{clippy_is_available, project, registry::Package};
+use cargo_test_support::{clippy_is_available, project, registry::Package};
 
 #[cargo_test]
 // Clippy should never be considered fresh.
diff --git a/tests/testsuite/collisions.rs b/tests/testsuite/collisions.rs
index bca9fb3f8c1..f1fb4bacfb6 100644
--- a/tests/testsuite/collisions.rs
+++ b/tests/testsuite/collisions.rs
@@ -1,4 +1,4 @@
-use crate::support::{basic_manifest, project};
+use cargo_test_support::{basic_manifest, project};
 use std::env;
 
 #[cargo_test]
diff --git a/tests/testsuite/concurrent.rs b/tests/testsuite/concurrent.rs
index 9336c51cdfb..43b4363c908 100644
--- a/tests/testsuite/concurrent.rs
+++ b/tests/testsuite/concurrent.rs
@@ -6,11 +6,11 @@ use std::sync::mpsc::channel;
 use std::thread;
 use std::{env, str};
 
-use crate::support::cargo_process;
-use crate::support::git;
-use crate::support::install::{assert_has_installed_exe, cargo_home};
-use crate::support::registry::Package;
-use crate::support::{basic_manifest, execs, project, slow_cpu_multiplier};
+use cargo_test_support::cargo_process;
+use cargo_test_support::git;
+use cargo_test_support::install::{assert_has_installed_exe, cargo_home};
+use cargo_test_support::registry::Package;
+use cargo_test_support::{basic_manifest, execs, project, slow_cpu_multiplier};
 use git2;
 
 fn pkg(name: &str, vers: &str) {
diff --git a/tests/testsuite/config.rs b/tests/testsuite/config.rs
index bd56e996e0a..d65fe7a9af0 100644
--- a/tests/testsuite/config.rs
+++ b/tests/testsuite/config.rs
@@ -5,16 +5,16 @@ use std::io;
 use std::os;
 use std::path::Path;
 
-use crate::support::{paths, project};
 use cargo::core::{enable_nightly_features, Shell};
 use cargo::util::config::{self, Config};
 use cargo::util::toml::{self, VecStringOrBool as VSOB};
+use cargo_test_support::{paths, project, t};
 use serde::Deserialize;
 
 fn lines_match(a: &str, b: &str) -> bool {
     // Perform a small amount of normalization for filesystem paths before we
     // send this to the `lines_match` function.
-    crate::support::lines_match(&a.replace("\\", "/"), &b.replace("\\", "/"))
+    cargo_test_support::lines_match(&a.replace("\\", "/"), &b.replace("\\", "/"))
 }
 
 #[cargo_test]
diff --git a/tests/testsuite/corrupt_git.rs b/tests/testsuite/corrupt_git.rs
index 16900e73ec3..39b9e258474 100644
--- a/tests/testsuite/corrupt_git.rs
+++ b/tests/testsuite/corrupt_git.rs
@@ -1,9 +1,9 @@
 use std::fs;
 use std::path::{Path, PathBuf};
 
-use crate::support::paths;
-use crate::support::{basic_manifest, git, project};
 use cargo::util::paths as cargopaths;
+use cargo_test_support::paths;
+use cargo_test_support::{basic_manifest, git, project};
 
 #[cargo_test]
 fn deleting_database_files() {
diff --git a/tests/testsuite/cross_compile.rs b/tests/testsuite/cross_compile.rs
index cf0be0e2786..671afe7003a 100644
--- a/tests/testsuite/cross_compile.rs
+++ b/tests/testsuite/cross_compile.rs
@@ -1,5 +1,5 @@
-use crate::support::{basic_bin_manifest, basic_manifest, cross_compile, project};
-use crate::support::{is_nightly, rustc_host};
+use cargo_test_support::{basic_bin_manifest, basic_manifest, cross_compile, project};
+use cargo_test_support::{is_nightly, rustc_host};
 
 #[cargo_test]
 fn simple_cross() {
diff --git a/tests/testsuite/cross_publish.rs b/tests/testsuite/cross_publish.rs
index 076a90361b4..95ed071a4e8 100644
--- a/tests/testsuite/cross_publish.rs
+++ b/tests/testsuite/cross_publish.rs
@@ -1,6 +1,6 @@
 use std::fs::File;
 
-use crate::support::{cross_compile, project, publish, registry};
+use cargo_test_support::{cross_compile, project, publish, registry};
 
 #[cargo_test]
 fn simple_cross_package() {
diff --git a/tests/testsuite/custom_target.rs b/tests/testsuite/custom_target.rs
index adcec16bb13..ca28b28238b 100644
--- a/tests/testsuite/custom_target.rs
+++ b/tests/testsuite/custom_target.rs
@@ -1,5 +1,5 @@
-use crate::support::is_nightly;
-use crate::support::{basic_manifest, project};
+use cargo_test_support::is_nightly;
+use cargo_test_support::{basic_manifest, project};
 
 #[cargo_test]
 fn custom_target_minimal() {
diff --git a/tests/testsuite/death.rs b/tests/testsuite/death.rs
index 1c1addb3311..9fae5448084 100644
--- a/tests/testsuite/death.rs
+++ b/tests/testsuite/death.rs
@@ -4,7 +4,7 @@ use std::net::TcpListener;
 use std::process::{Child, Stdio};
 use std::thread;
 
-use crate::{support::project, support::slow_cpu_multiplier};
+use cargo_test_support::{project, slow_cpu_multiplier};
 
 #[cfg(unix)]
 fn enabled() -> bool {
diff --git a/tests/testsuite/dep_info.rs b/tests/testsuite/dep_info.rs
index 439621e42e9..dc116f848b6 100644
--- a/tests/testsuite/dep_info.rs
+++ b/tests/testsuite/dep_info.rs
@@ -1,6 +1,6 @@
-use crate::support::paths::{self, CargoPathExt};
-use crate::support::registry::Package;
-use crate::support::{
+use cargo_test_support::paths::{self, CargoPathExt};
+use cargo_test_support::registry::Package;
+use cargo_test_support::{
     basic_bin_manifest, basic_manifest, is_nightly, main_file, project, rustc_host, Project,
 };
 use filetime::FileTime;
@@ -478,7 +478,7 @@ fn canonical_path() {
         // See https://github.com/rust-lang/rust/issues/63012
         return;
     }
-    if !crate::support::symlink_supported() {
+    if !cargo_test_support::symlink_supported() {
         return;
     }
     Package::new("regdep", "0.1.0")
diff --git a/tests/testsuite/directory.rs b/tests/testsuite/directory.rs
index d4e7701497b..a7d60d1a7d2 100644
--- a/tests/testsuite/directory.rs
+++ b/tests/testsuite/directory.rs
@@ -5,11 +5,11 @@ use std::str;
 
 use serde::Serialize;
 
-use crate::support::cargo_process;
-use crate::support::git;
-use crate::support::paths;
-use crate::support::registry::{cksum, Package};
-use crate::support::{basic_manifest, project, ProjectBuilder};
+use cargo_test_support::cargo_process;
+use cargo_test_support::git;
+use cargo_test_support::paths;
+use cargo_test_support::registry::{cksum, Package};
+use cargo_test_support::{basic_manifest, project, t, ProjectBuilder};
 
 fn setup() {
     let root = paths::root();
diff --git a/tests/testsuite/doc.rs b/tests/testsuite/doc.rs
index f2909b1321f..53470eecf4f 100644
--- a/tests/testsuite/doc.rs
+++ b/tests/testsuite/doc.rs
@@ -2,10 +2,10 @@ use std::fs::{self, File};
 use std::io::Read;
 use std::str;
 
-use crate::support::paths::CargoPathExt;
-use crate::support::registry::Package;
-use crate::support::{basic_lib_manifest, basic_manifest, git, project};
-use crate::support::{is_nightly, rustc_host};
+use cargo_test_support::paths::CargoPathExt;
+use cargo_test_support::registry::Package;
+use cargo_test_support::{basic_lib_manifest, basic_manifest, git, project};
+use cargo_test_support::{is_nightly, rustc_host};
 
 #[cargo_test]
 fn simple() {
diff --git a/tests/testsuite/edition.rs b/tests/testsuite/edition.rs
index 5d3f04d9f5a..7007f67a462 100644
--- a/tests/testsuite/edition.rs
+++ b/tests/testsuite/edition.rs
@@ -1,4 +1,4 @@
-use crate::support::{basic_lib_manifest, project};
+use cargo_test_support::{basic_lib_manifest, project};
 
 #[cargo_test]
 fn edition_works_for_build_script() {
diff --git a/tests/testsuite/features.rs b/tests/testsuite/features.rs
index fae985c3a4e..a167b78185e 100644
--- a/tests/testsuite/features.rs
+++ b/tests/testsuite/features.rs
@@ -1,9 +1,9 @@
 use std::fs::File;
 use std::io::prelude::*;
 
-use crate::support::paths::CargoPathExt;
-use crate::support::registry::Package;
-use crate::support::{basic_manifest, project};
+use cargo_test_support::paths::CargoPathExt;
+use cargo_test_support::registry::Package;
+use cargo_test_support::{basic_manifest, project, t};
 
 #[cargo_test]
 fn invalid1() {
diff --git a/tests/testsuite/fetch.rs b/tests/testsuite/fetch.rs
index 088f683c1bc..2978962025f 100644
--- a/tests/testsuite/fetch.rs
+++ b/tests/testsuite/fetch.rs
@@ -1,6 +1,6 @@
-use crate::support::registry::Package;
-use crate::support::rustc_host;
-use crate::support::{basic_manifest, cross_compile, project};
+use cargo_test_support::registry::Package;
+use cargo_test_support::rustc_host;
+use cargo_test_support::{basic_manifest, cross_compile, project};
 
 #[cargo_test]
 fn no_deps() {
diff --git a/tests/testsuite/fix.rs b/tests/testsuite/fix.rs
index eaaf4cc2f19..f30dbf28933 100644
--- a/tests/testsuite/fix.rs
+++ b/tests/testsuite/fix.rs
@@ -1,7 +1,7 @@
 use std::fs::File;
 
-use crate::support::git;
-use crate::support::{basic_manifest, clippy_is_available, is_nightly, project};
+use cargo_test_support::git;
+use cargo_test_support::{basic_manifest, clippy_is_available, is_nightly, project};
 
 use std::io::Write;
 
diff --git a/tests/testsuite/freshness.rs b/tests/testsuite/freshness.rs
index 03777719455..1b4527c3905 100644
--- a/tests/testsuite/freshness.rs
+++ b/tests/testsuite/freshness.rs
@@ -7,10 +7,10 @@ use std::path::{Path, PathBuf};
 use std::thread;
 use std::time::SystemTime;
 
-use crate::support::paths::{self, CargoPathExt};
-use crate::support::registry::Package;
-use crate::support::sleep_ms;
-use crate::support::{basic_manifest, is_coarse_mtime, project};
+use cargo_test_support::paths::{self, CargoPathExt};
+use cargo_test_support::registry::Package;
+use cargo_test_support::sleep_ms;
+use cargo_test_support::{basic_manifest, is_coarse_mtime, project};
 
 #[cargo_test]
 fn modifying_and_moving() {
diff --git a/tests/testsuite/generate_lockfile.rs b/tests/testsuite/generate_lockfile.rs
index 0df2c091694..23a71408b41 100644
--- a/tests/testsuite/generate_lockfile.rs
+++ b/tests/testsuite/generate_lockfile.rs
@@ -1,8 +1,8 @@
 use std::fs::{self, File};
 use std::io::prelude::*;
 
-use crate::support::registry::Package;
-use crate::support::{basic_manifest, paths, project, ProjectBuilder};
+use cargo_test_support::registry::Package;
+use cargo_test_support::{basic_manifest, paths, project, ProjectBuilder};
 
 #[cargo_test]
 fn adding_and_removing_packages() {
diff --git a/tests/testsuite/git.rs b/tests/testsuite/git.rs
index cdc2dd4ef0a..523fbb79434 100644
--- a/tests/testsuite/git.rs
+++ b/tests/testsuite/git.rs
@@ -8,10 +8,9 @@ use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::Arc;
 use std::thread;
 
-use crate::support::paths::{self, CargoPathExt};
-use crate::support::sleep_ms;
-use crate::support::Project;
-use crate::support::{basic_lib_manifest, basic_manifest, git, main_file, path2url, project};
+use cargo_test_support::paths::{self, CargoPathExt};
+use cargo_test_support::{basic_lib_manifest, basic_manifest, git, main_file, path2url, project};
+use cargo_test_support::{sleep_ms, t, Project};
 
 fn disable_git_cli() -> bool {
     // mingw git on Windows does not support Windows-style file URIs.
diff --git a/tests/testsuite/init.rs b/tests/testsuite/init.rs
index 84e0b9d3691..e0e6620be60 100644
--- a/tests/testsuite/init.rs
+++ b/tests/testsuite/init.rs
@@ -1,13 +1,13 @@
-use crate::support;
+use cargo_test_support;
 use std::env;
 use std::fs::{self, File};
 use std::io::prelude::*;
 use std::process::Command;
 
-use crate::support::{paths, Execs};
+use cargo_test_support::{paths, Execs};
 
 fn cargo_process(s: &str) -> Execs {
-    let mut execs = support::cargo_process(s);
+    let mut execs = cargo_test_support::cargo_process(s);
     execs.cwd(&paths::root()).env("HOME", &paths::home());
     execs
 }
diff --git a/tests/testsuite/install.rs b/tests/testsuite/install.rs
index ef909f1eb23..2a829bc30b2 100644
--- a/tests/testsuite/install.rs
+++ b/tests/testsuite/install.rs
@@ -3,13 +3,14 @@ use std::io::prelude::*;
 
 use git2;
 
-use crate::support;
-use crate::support::cross_compile;
-use crate::support::git;
-use crate::support::install::{assert_has_installed_exe, assert_has_not_installed_exe, cargo_home};
-use crate::support::paths;
-use crate::support::registry::Package;
-use crate::support::{basic_manifest, cargo_process, project};
+use cargo_test_support::cross_compile;
+use cargo_test_support::git;
+use cargo_test_support::install::{
+    assert_has_installed_exe, assert_has_not_installed_exe, cargo_home,
+};
+use cargo_test_support::paths;
+use cargo_test_support::registry::Package;
+use cargo_test_support::{basic_manifest, cargo_process, project};
 
 fn pkg(name: &str, vers: &str) {
     Package::new(name, vers)
@@ -1057,7 +1058,7 @@ fn install_target_native() {
     pkg("foo", "0.1.0");
 
     cargo_process("install foo --target")
-        .arg(support::rustc_host())
+        .arg(cargo_test_support::rustc_host())
         .run();
     assert_has_installed_exe(cargo_home(), "foo");
 }
diff --git a/tests/testsuite/install_upgrade.rs b/tests/testsuite/install_upgrade.rs
index 821bda7c383..256bb164de3 100644
--- a/tests/testsuite/install_upgrade.rs
+++ b/tests/testsuite/install_upgrade.rs
@@ -5,10 +5,10 @@ use std::fs;
 use std::path::PathBuf;
 use std::sync::atomic::{AtomicUsize, Ordering};
 
-use crate::support::install::{cargo_home, exe};
-use crate::support::paths::CargoPathExt;
-use crate::support::registry::Package;
-use crate::support::{
+use cargo_test_support::install::{cargo_home, exe};
+use cargo_test_support::paths::CargoPathExt;
+use cargo_test_support::registry::Package;
+use cargo_test_support::{
     basic_manifest, cargo_process, cross_compile, execs, git, process, project, Execs,
 };
 
diff --git a/tests/testsuite/jobserver.rs b/tests/testsuite/jobserver.rs
index 59300b6762c..b0d90cc36f5 100644
--- a/tests/testsuite/jobserver.rs
+++ b/tests/testsuite/jobserver.rs
@@ -2,7 +2,7 @@ use std::net::TcpListener;
 use std::process::Command;
 use std::thread;
 
-use crate::support::{cargo_exe, project};
+use cargo_test_support::{cargo_exe, project};
 
 #[cargo_test]
 fn jobserver_exists() {
diff --git a/tests/testsuite/list_targets.rs b/tests/testsuite/list_targets.rs
index 9db79afb525..a370a368292 100644
--- a/tests/testsuite/list_targets.rs
+++ b/tests/testsuite/list_targets.rs
@@ -1,4 +1,4 @@
-use crate::support::project;
+use cargo_test_support::project;
 
 const EXAMPLE: u8 = 0x1;
 const BIN: u8 = 0x2;
diff --git a/tests/testsuite/local_registry.rs b/tests/testsuite/local_registry.rs
index 7df486dd997..8cffb29568e 100644
--- a/tests/testsuite/local_registry.rs
+++ b/tests/testsuite/local_registry.rs
@@ -1,9 +1,9 @@
 use std::fs::{self, File};
 use std::io::prelude::*;
 
-use crate::support::paths::{self, CargoPathExt};
-use crate::support::registry::{registry_path, Package};
-use crate::support::{basic_manifest, project};
+use cargo_test_support::paths::{self, CargoPathExt};
+use cargo_test_support::registry::{registry_path, Package};
+use cargo_test_support::{basic_manifest, project, t};
 
 fn setup() {
     let root = paths::root();
diff --git a/tests/testsuite/lockfile_compat.rs b/tests/testsuite/lockfile_compat.rs
index 85ee88f16c2..abe4e4397f3 100644
--- a/tests/testsuite/lockfile_compat.rs
+++ b/tests/testsuite/lockfile_compat.rs
@@ -1,6 +1,6 @@
-use crate::support::git;
-use crate::support::registry::Package;
-use crate::support::{basic_manifest, lines_match, project};
+use cargo_test_support::git;
+use cargo_test_support::registry::Package;
+use cargo_test_support::{basic_manifest, lines_match, project};
 
 #[cargo_test]
 fn oldest_lockfile_still_works() {
diff --git a/tests/testsuite/login.rs b/tests/testsuite/login.rs
index d203d818fdb..69822207ada 100644
--- a/tests/testsuite/login.rs
+++ b/tests/testsuite/login.rs
@@ -2,11 +2,11 @@ use std::fs::{self, File};
 use std::io::prelude::*;
 use std::path::PathBuf;
 
-use crate::support::cargo_process;
-use crate::support::install::cargo_home;
-use crate::support::registry::{self, registry_url};
 use cargo::core::Shell;
 use cargo::util::config::Config;
+use cargo_test_support::install::cargo_home;
+use cargo_test_support::registry::{self, registry_url};
+use cargo_test_support::{cargo_process, t};
 use toml;
 
 const TOKEN: &str = "test-token";
diff --git a/tests/testsuite/main.rs b/tests/testsuite/main.rs
index 60002361b49..237a58ac7d6 100644
--- a/tests/testsuite/main.rs
+++ b/tests/testsuite/main.rs
@@ -9,9 +9,6 @@
 #[macro_use]
 extern crate cargo_test_macro;
 
-#[macro_use]
-mod support;
-
 mod alt_registry;
 mod bad_config;
 mod bad_manifest_path;
@@ -104,5 +101,5 @@ mod workspaces;
 #[cargo_test]
 fn aaa_trigger_cross_compile_disabled_check() {
     // This triggers the cross compile disabled check to run ASAP, see #5141
-    support::cross_compile::disabled();
+    cargo_test_support::cross_compile::disabled();
 }
diff --git a/tests/testsuite/member_errors.rs b/tests/testsuite/member_errors.rs
index a4d17d8f1c7..09e7a7961b5 100644
--- a/tests/testsuite/member_errors.rs
+++ b/tests/testsuite/member_errors.rs
@@ -3,9 +3,9 @@ use cargo::core::{compiler::CompileMode, Shell, Workspace};
 use cargo::ops::{self, CompileOptions};
 use cargo::util::{config::Config, errors::ManifestError};
 
-use crate::support::install::cargo_home;
-use crate::support::project;
-use crate::support::registry;
+use cargo_test_support::install::cargo_home;
+use cargo_test_support::project;
+use cargo_test_support::registry;
 
 /// Tests inclusion of a `ManifestError` pointing to a member manifest
 /// when that manifest fails to deserialize.
diff --git a/tests/testsuite/message_format.rs b/tests/testsuite/message_format.rs
index 06969e7a631..361c03fc7db 100644
--- a/tests/testsuite/message_format.rs
+++ b/tests/testsuite/message_format.rs
@@ -1,8 +1,8 @@
-use crate::support::{basic_manifest, project};
+use cargo_test_support::{basic_manifest, project};
 
 #[cargo_test]
 fn cannot_specify_two() {
-    if !crate::support::is_nightly() {
+    if !cargo_test_support::is_nightly() {
         return;
     }
 
@@ -26,7 +26,7 @@ fn cannot_specify_two() {
 
 #[cargo_test]
 fn double_json_works() {
-    if !crate::support::is_nightly() {
+    if !cargo_test_support::is_nightly() {
         return;
     }
 
@@ -51,7 +51,7 @@ fn double_json_works() {
 
 #[cargo_test]
 fn cargo_renders() {
-    if !crate::support::is_nightly() {
+    if !cargo_test_support::is_nightly() {
         return;
     }
 
@@ -87,7 +87,7 @@ error[..]`main`[..]
 
 #[cargo_test]
 fn cargo_renders_short() {
-    if !crate::support::is_nightly() {
+    if !cargo_test_support::is_nightly() {
         return;
     }
 
@@ -110,7 +110,7 @@ error[..]`main`[..]
 
 #[cargo_test]
 fn cargo_renders_ansi() {
-    if !crate::support::is_nightly() {
+    if !cargo_test_support::is_nightly() {
         return;
     }
 
diff --git a/tests/testsuite/metabuild.rs b/tests/testsuite/metabuild.rs
index 2f6486beee6..60b3f6ae2b3 100644
--- a/tests/testsuite/metabuild.rs
+++ b/tests/testsuite/metabuild.rs
@@ -1,4 +1,4 @@
-use crate::support::{
+use cargo_test_support::{
     basic_lib_manifest, basic_manifest, is_coarse_mtime, project, registry::Package, rustc_host,
     Project,
 };
diff --git a/tests/testsuite/metadata.rs b/tests/testsuite/metadata.rs
index 713c9d4a83a..ef37256a0ea 100644
--- a/tests/testsuite/metadata.rs
+++ b/tests/testsuite/metadata.rs
@@ -1,5 +1,5 @@
-use crate::support::registry::Package;
-use crate::support::{basic_bin_manifest, basic_lib_manifest, main_file, project};
+use cargo_test_support::registry::Package;
+use cargo_test_support::{basic_bin_manifest, basic_lib_manifest, main_file, project};
 
 #[cargo_test]
 fn cargo_metadata_simple() {
diff --git a/tests/testsuite/mock-std/Cargo.toml b/tests/testsuite/mock-std/Cargo.toml
new file mode 100644
index 00000000000..a2fdae3b7f0
--- /dev/null
+++ b/tests/testsuite/mock-std/Cargo.toml
@@ -0,0 +1,9 @@
+[workspace]
+members = [
+  "src/libtest",
+]
+
+[patch.crates-io]
+rustc-std-workspace-std = { path = 'src/tools/rustc-std-workspace-std' }
+rustc-std-workspace-core = { path = 'src/tools/rustc-std-workspace-core' }
+rustc-std-workspace-alloc = { path = 'src/tools/rustc-std-workspace-alloc' }
diff --git a/tests/testsuite/mock-std/src/liballoc/Cargo.toml b/tests/testsuite/mock-std/src/liballoc/Cargo.toml
new file mode 100644
index 00000000000..128600df51a
--- /dev/null
+++ b/tests/testsuite/mock-std/src/liballoc/Cargo.toml
@@ -0,0 +1,11 @@
+[package]
+name = "alloc"
+version = "0.1.0"
+authors = ["Alex Crichton <alex@alexcrichton.com>"]
+edition = "2018"
+
+[lib]
+path = "lib.rs"
+
+[dependencies]
+core = { path = "../libcore" }
diff --git a/tests/testsuite/mock-std/src/liballoc/lib.rs b/tests/testsuite/mock-std/src/liballoc/lib.rs
new file mode 100644
index 00000000000..e29525b6a50
--- /dev/null
+++ b/tests/testsuite/mock-std/src/liballoc/lib.rs
@@ -0,0 +1 @@
+pub fn custom_api() {}
diff --git a/tests/testsuite/mock-std/src/libcompiler_builtins/Cargo.toml b/tests/testsuite/mock-std/src/libcompiler_builtins/Cargo.toml
new file mode 100644
index 00000000000..27141f23250
--- /dev/null
+++ b/tests/testsuite/mock-std/src/libcompiler_builtins/Cargo.toml
@@ -0,0 +1,11 @@
+[package]
+name = "compiler_builtins"
+version = "0.1.0"
+authors = ["Alex Crichton <alex@alexcrichton.com>"]
+edition = "2018"
+
+[lib]
+path = "lib.rs"
+
+[dependencies]
+core = { path = "../libcore" }
diff --git a/tests/testsuite/mock-std/src/libcompiler_builtins/lib.rs b/tests/testsuite/mock-std/src/libcompiler_builtins/lib.rs
new file mode 100644
index 00000000000..65e2cc34045
--- /dev/null
+++ b/tests/testsuite/mock-std/src/libcompiler_builtins/lib.rs
@@ -0,0 +1 @@
+// intentionally blank
diff --git a/tests/testsuite/mock-std/src/libcore/Cargo.toml b/tests/testsuite/mock-std/src/libcore/Cargo.toml
new file mode 100644
index 00000000000..b448bdb085d
--- /dev/null
+++ b/tests/testsuite/mock-std/src/libcore/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "core"
+version = "0.1.0"
+authors = ["Alex Crichton <alex@alexcrichton.com>"]
+edition = "2018"
+
+[lib]
+path = "lib.rs"
diff --git a/tests/testsuite/mock-std/src/libcore/build.rs b/tests/testsuite/mock-std/src/libcore/build.rs
new file mode 100644
index 00000000000..53d4e145d35
--- /dev/null
+++ b/tests/testsuite/mock-std/src/libcore/build.rs
@@ -0,0 +1,23 @@
+//! This build script is basically the whole hack that makes this entire "mock
+//! std" feature work. Here we print out `rustc-link-search` pointing to the
+//! sysroot of the actual compiler itself, and that way we can indeed implicitly
+//! pull in those crates, but only via `extern crate`. That means that we can
+//! build tiny shim core/std/etc crates while they actually load all the various
+//! language/library details from the actual crates, meaning that instead of
+//! literally compiling libstd we compile just our own tiny shims.
+
+use std::process::Command;
+use std::env;
+
+fn main() {
+    let output = Command::new("rustc")
+        .arg("--print")
+        .arg("sysroot")
+        .output()
+        .unwrap();
+    assert!(output.status.success());
+    let stdout = String::from_utf8(output.stdout).unwrap();
+    let stdout = stdout.trim();
+    let host = env::var("HOST").unwrap();
+    println!("cargo:rustc-link-search={}/lib/rustlib/{}/lib", stdout, host);
+}
diff --git a/tests/testsuite/mock-std/src/libcore/lib.rs b/tests/testsuite/mock-std/src/libcore/lib.rs
new file mode 100644
index 00000000000..73e79b9a905
--- /dev/null
+++ b/tests/testsuite/mock-std/src/libcore/lib.rs
@@ -0,0 +1,4 @@
+#![no_std]
+pub use core::*;
+
+pub fn custom_api() {}
diff --git a/tests/testsuite/mock-std/src/libpanic_unwind/Cargo.toml b/tests/testsuite/mock-std/src/libpanic_unwind/Cargo.toml
new file mode 100644
index 00000000000..af06d7736e1
--- /dev/null
+++ b/tests/testsuite/mock-std/src/libpanic_unwind/Cargo.toml
@@ -0,0 +1,11 @@
+[package]
+name = "panic_unwind"
+version = "0.1.0"
+authors = ["Alex Crichton <alex@alexcrichton.com>"]
+edition = "2018"
+
+[lib]
+path = "lib.rs"
+
+[dependencies]
+core = { path = "../libcore" }
diff --git a/tests/testsuite/mock-std/src/libpanic_unwind/lib.rs b/tests/testsuite/mock-std/src/libpanic_unwind/lib.rs
new file mode 100644
index 00000000000..6af65d87507
--- /dev/null
+++ b/tests/testsuite/mock-std/src/libpanic_unwind/lib.rs
@@ -0,0 +1,5 @@
+#![feature(panic_unwind, panic_runtime)]
+#![panic_runtime]
+#![no_std]
+
+extern crate panic_unwind;
diff --git a/tests/testsuite/mock-std/src/libproc_macro/Cargo.toml b/tests/testsuite/mock-std/src/libproc_macro/Cargo.toml
new file mode 100644
index 00000000000..bc93bfcc785
--- /dev/null
+++ b/tests/testsuite/mock-std/src/libproc_macro/Cargo.toml
@@ -0,0 +1,11 @@
+[package]
+name = "proc_macro"
+version = "0.1.0"
+authors = ["Alex Crichton <alex@alexcrichton.com>"]
+edition = "2018"
+
+[lib]
+path = "lib.rs"
+
+[dependencies]
+std = { path = "../libstd" }
diff --git a/tests/testsuite/mock-std/src/libproc_macro/lib.rs b/tests/testsuite/mock-std/src/libproc_macro/lib.rs
new file mode 100644
index 00000000000..73825ac07c2
--- /dev/null
+++ b/tests/testsuite/mock-std/src/libproc_macro/lib.rs
@@ -0,0 +1,3 @@
+extern crate proc_macro;
+pub use proc_macro::*;
+pub fn custom_api() {}
diff --git a/tests/testsuite/mock-std/src/libstd/Cargo.toml b/tests/testsuite/mock-std/src/libstd/Cargo.toml
new file mode 100644
index 00000000000..9338f036826
--- /dev/null
+++ b/tests/testsuite/mock-std/src/libstd/Cargo.toml
@@ -0,0 +1,15 @@
+[package]
+name = "std"
+version = "0.1.0"
+authors = ["Alex Crichton <alex@alexcrichton.com>"]
+edition = "2018"
+
+[lib]
+path = "lib.rs"
+
+[dependencies]
+core = { path = "../libcore" }
+compiler_builtins = { path = "../libcompiler_builtins" }
+panic_unwind = { path = "../libpanic_unwind" }
+registry-dep-using-core = { version = "1.0", features = ['mockbuild'] }
+registry-dep-using-alloc = { version = "1.0", features = ['mockbuild'] }
diff --git a/tests/testsuite/mock-std/src/libstd/lib.rs b/tests/testsuite/mock-std/src/libstd/lib.rs
new file mode 100644
index 00000000000..e7e64f1f643
--- /dev/null
+++ b/tests/testsuite/mock-std/src/libstd/lib.rs
@@ -0,0 +1,6 @@
+pub use std::*;
+
+pub fn custom_api() {
+    registry_dep_using_core::custom_api();
+    registry_dep_using_alloc::custom_api();
+}
diff --git a/tests/testsuite/mock-std/src/libtest/Cargo.toml b/tests/testsuite/mock-std/src/libtest/Cargo.toml
new file mode 100644
index 00000000000..a81a2dd6a2a
--- /dev/null
+++ b/tests/testsuite/mock-std/src/libtest/Cargo.toml
@@ -0,0 +1,17 @@
+[package]
+name = "test"
+version = "0.1.0"
+authors = ["Alex Crichton <alex@alexcrichton.com>"]
+edition = "2018"
+
+[lib]
+path = "lib.rs"
+
+[dependencies]
+proc_macro = { path = "../libproc_macro" }
+registry-dep-using-std = { version = "1.0", features = ['mockbuild'] }
+std = { path = "../libstd" }
+
+[features]
+panic-unwind = []
+backtrace = []
diff --git a/tests/testsuite/mock-std/src/libtest/lib.rs b/tests/testsuite/mock-std/src/libtest/lib.rs
new file mode 100644
index 00000000000..34c0e532ba6
--- /dev/null
+++ b/tests/testsuite/mock-std/src/libtest/lib.rs
@@ -0,0 +1,9 @@
+#![feature(test)]
+
+extern crate test;
+
+pub use test::*;
+
+pub fn custom_api() {
+    registry_dep_using_std::custom_api();
+}
diff --git a/tests/testsuite/mock-std/src/tools/rustc-std-workspace-alloc/Cargo.toml b/tests/testsuite/mock-std/src/tools/rustc-std-workspace-alloc/Cargo.toml
new file mode 100644
index 00000000000..54d9ff4fd59
--- /dev/null
+++ b/tests/testsuite/mock-std/src/tools/rustc-std-workspace-alloc/Cargo.toml
@@ -0,0 +1,12 @@
+[package]
+name = "rustc-std-workspace-alloc"
+version = "1.9.0"
+authors = ["Alex Crichton <alex@alexcrichton.com>"]
+edition = "2018"
+
+[lib]
+name = "alloc"
+path = "lib.rs"
+
+[dependencies]
+alloc = { path = "../../liballoc" }
diff --git a/tests/testsuite/mock-std/src/tools/rustc-std-workspace-alloc/lib.rs b/tests/testsuite/mock-std/src/tools/rustc-std-workspace-alloc/lib.rs
new file mode 100644
index 00000000000..2bbfa1a49a7
--- /dev/null
+++ b/tests/testsuite/mock-std/src/tools/rustc-std-workspace-alloc/lib.rs
@@ -0,0 +1,3 @@
+#![no_std]
+
+pub use alloc::*;
diff --git a/tests/testsuite/mock-std/src/tools/rustc-std-workspace-core/Cargo.toml b/tests/testsuite/mock-std/src/tools/rustc-std-workspace-core/Cargo.toml
new file mode 100644
index 00000000000..d62698f62f3
--- /dev/null
+++ b/tests/testsuite/mock-std/src/tools/rustc-std-workspace-core/Cargo.toml
@@ -0,0 +1,12 @@
+[package]
+name = "rustc-std-workspace-core"
+version = "1.9.0"
+authors = ["Alex Crichton <alex@alexcrichton.com>"]
+edition = "2018"
+
+[lib]
+name = "core"
+path = "lib.rs"
+
+[dependencies]
+core = { path = "../../libcore" }
diff --git a/tests/testsuite/mock-std/src/tools/rustc-std-workspace-core/lib.rs b/tests/testsuite/mock-std/src/tools/rustc-std-workspace-core/lib.rs
new file mode 100644
index 00000000000..816251790a9
--- /dev/null
+++ b/tests/testsuite/mock-std/src/tools/rustc-std-workspace-core/lib.rs
@@ -0,0 +1,3 @@
+#![no_std]
+
+pub use core::*;
diff --git a/tests/testsuite/mock-std/src/tools/rustc-std-workspace-std/Cargo.toml b/tests/testsuite/mock-std/src/tools/rustc-std-workspace-std/Cargo.toml
new file mode 100644
index 00000000000..0a4bd3a7e46
--- /dev/null
+++ b/tests/testsuite/mock-std/src/tools/rustc-std-workspace-std/Cargo.toml
@@ -0,0 +1,12 @@
+[package]
+name = "rustc-std-workspace-std"
+version = "1.9.0"
+authors = ["Alex Crichton <alex@alexcrichton.com>"]
+edition = "2018"
+
+[lib]
+name = "std"
+path = "lib.rs"
+
+[dependencies]
+std = { path = "../../libstd" }
diff --git a/tests/testsuite/mock-std/src/tools/rustc-std-workspace-std/lib.rs b/tests/testsuite/mock-std/src/tools/rustc-std-workspace-std/lib.rs
new file mode 100644
index 00000000000..f40d09cafbb
--- /dev/null
+++ b/tests/testsuite/mock-std/src/tools/rustc-std-workspace-std/lib.rs
@@ -0,0 +1 @@
+pub use std::*;
diff --git a/tests/testsuite/net_config.rs b/tests/testsuite/net_config.rs
index 7d8456ca776..e62e0bd577a 100644
--- a/tests/testsuite/net_config.rs
+++ b/tests/testsuite/net_config.rs
@@ -1,4 +1,4 @@
-use crate::support::project;
+use cargo_test_support::project;
 
 #[cargo_test]
 fn net_retry_loads_from_config() {
diff --git a/tests/testsuite/new.rs b/tests/testsuite/new.rs
index ee6408026e4..08894c93951 100644
--- a/tests/testsuite/new.rs
+++ b/tests/testsuite/new.rs
@@ -2,8 +2,8 @@ use std::env;
 use std::fs::{self, File};
 use std::io::prelude::*;
 
-use crate::support::paths;
-use crate::support::{cargo_process, git_process};
+use cargo_test_support::paths;
+use cargo_test_support::{cargo_process, git_process};
 
 fn create_empty_gitconfig() {
     // This helps on Windows where libgit2 is very aggressive in attempting to
diff --git a/tests/testsuite/offline.rs b/tests/testsuite/offline.rs
index c8736232da2..0ca57953390 100644
--- a/tests/testsuite/offline.rs
+++ b/tests/testsuite/offline.rs
@@ -1,4 +1,4 @@
-use crate::support::{basic_manifest, git, main_file, path2url, project, registry::Package};
+use cargo_test_support::{basic_manifest, git, main_file, path2url, project, registry::Package};
 use std::fs;
 
 #[cargo_test]
diff --git a/tests/testsuite/out_dir.rs b/tests/testsuite/out_dir.rs
index e57d98b9d69..24aa304b08a 100644
--- a/tests/testsuite/out_dir.rs
+++ b/tests/testsuite/out_dir.rs
@@ -2,8 +2,8 @@ use std::env;
 use std::fs::{self, File};
 use std::path::Path;
 
-use crate::support::sleep_ms;
-use crate::support::{basic_manifest, project};
+use cargo_test_support::sleep_ms;
+use cargo_test_support::{basic_manifest, project};
 
 #[cargo_test]
 fn binary_with_debug() {
diff --git a/tests/testsuite/overrides.rs b/tests/testsuite/overrides.rs
index 1a9dd1c592f..341dba6f4b6 100644
--- a/tests/testsuite/overrides.rs
+++ b/tests/testsuite/overrides.rs
@@ -1,7 +1,7 @@
-use crate::support::git;
-use crate::support::paths;
-use crate::support::registry::Package;
-use crate::support::{basic_manifest, project};
+use cargo_test_support::git;
+use cargo_test_support::paths;
+use cargo_test_support::registry::Package;
+use cargo_test_support::{basic_manifest, project};
 
 #[cargo_test]
 fn override_simple() {
diff --git a/tests/testsuite/package.rs b/tests/testsuite/package.rs
index 9aa6ddc15e2..feb272f78da 100644
--- a/tests/testsuite/package.rs
+++ b/tests/testsuite/package.rs
@@ -3,11 +3,11 @@ use std::fs::File;
 use std::io::prelude::*;
 use std::path::Path;
 
-use crate::support::paths::CargoPathExt;
-use crate::support::registry::Package;
-use crate::support::{
+use cargo_test_support::paths::CargoPathExt;
+use cargo_test_support::registry::Package;
+use cargo_test_support::{
     basic_manifest, cargo_process, git, path2url, paths, project, publish::validate_crate_contents,
-    registry, symlink_supported,
+    registry, symlink_supported, t,
 };
 use git2;
 
diff --git a/tests/testsuite/patch.rs b/tests/testsuite/patch.rs
index 8c1459c916c..e2357ffceac 100644
--- a/tests/testsuite/patch.rs
+++ b/tests/testsuite/patch.rs
@@ -1,10 +1,10 @@
 use std::fs::{self, File};
 use std::io::{Read, Write};
 
-use crate::support::git;
-use crate::support::paths;
-use crate::support::registry::Package;
-use crate::support::{basic_manifest, project};
+use cargo_test_support::git;
+use cargo_test_support::paths;
+use cargo_test_support::registry::Package;
+use cargo_test_support::{basic_manifest, project, t};
 use toml;
 
 #[cargo_test]
@@ -1187,7 +1187,7 @@ fn patch_same_version() {
         .file("src/lib.rs", "")
         .build();
 
-    crate::support::registry::init();
+    cargo_test_support::registry::init();
 
     let p = project()
         .file(
@@ -1236,7 +1236,7 @@ fn two_semver_compatible() {
         .file("src/lib.rs", "")
         .build();
 
-    crate::support::registry::init();
+    cargo_test_support::registry::init();
 
     let p = project()
         .file(
@@ -1291,7 +1291,7 @@ fn multipatch_select_big() {
         .file("src/lib.rs", "")
         .build();
 
-    crate::support::registry::init();
+    cargo_test_support::registry::init();
 
     let p = project()
         .file(
diff --git a/tests/testsuite/path.rs b/tests/testsuite/path.rs
index 226668ceb63..362531ee592 100644
--- a/tests/testsuite/path.rs
+++ b/tests/testsuite/path.rs
@@ -1,10 +1,10 @@
 use std::fs::{self, File};
 use std::io::prelude::*;
 
-use crate::support::paths::{self, CargoPathExt};
-use crate::support::registry::Package;
-use crate::support::sleep_ms;
-use crate::support::{basic_lib_manifest, basic_manifest, main_file, project};
+use cargo_test_support::paths::{self, CargoPathExt};
+use cargo_test_support::registry::Package;
+use cargo_test_support::{basic_lib_manifest, basic_manifest, main_file, project};
+use cargo_test_support::{sleep_ms, t};
 
 #[cargo_test]
 // I have no idea why this is failing spuriously on Windows;
diff --git a/tests/testsuite/plugins.rs b/tests/testsuite/plugins.rs
index 1eda532b419..54701393496 100644
--- a/tests/testsuite/plugins.rs
+++ b/tests/testsuite/plugins.rs
@@ -1,5 +1,5 @@
-use crate::support::{basic_manifest, project};
-use crate::support::{is_nightly, rustc_host};
+use cargo_test_support::{basic_manifest, project};
+use cargo_test_support::{is_nightly, rustc_host};
 
 #[cargo_test]
 fn plugin_to_the_max() {
diff --git a/tests/testsuite/proc_macro.rs b/tests/testsuite/proc_macro.rs
index 8e9ee23edcd..d3774bf09c6 100644
--- a/tests/testsuite/proc_macro.rs
+++ b/tests/testsuite/proc_macro.rs
@@ -1,5 +1,5 @@
-use crate::support::is_nightly;
-use crate::support::project;
+use cargo_test_support::is_nightly;
+use cargo_test_support::project;
 
 #[cargo_test]
 fn probe_cfg_before_crate_type_discovery() {
diff --git a/tests/testsuite/profile_config.rs b/tests/testsuite/profile_config.rs
index 6513177737b..87b571a62bd 100644
--- a/tests/testsuite/profile_config.rs
+++ b/tests/testsuite/profile_config.rs
@@ -1,4 +1,4 @@
-use crate::support::{basic_lib_manifest, is_nightly, paths, project};
+use cargo_test_support::{basic_lib_manifest, is_nightly, paths, project};
 
 #[cargo_test]
 fn profile_config_gated() {
diff --git a/tests/testsuite/profile_overrides.rs b/tests/testsuite/profile_overrides.rs
index 17b3c25c18b..a3f867a64da 100644
--- a/tests/testsuite/profile_overrides.rs
+++ b/tests/testsuite/profile_overrides.rs
@@ -1,5 +1,5 @@
-use crate::support::registry::Package;
-use crate::support::{basic_lib_manifest, basic_manifest, project};
+use cargo_test_support::registry::Package;
+use cargo_test_support::{basic_lib_manifest, basic_manifest, project};
 
 #[cargo_test]
 fn profile_override_gated() {
diff --git a/tests/testsuite/profile_targets.rs b/tests/testsuite/profile_targets.rs
index 718ec2fb211..0532656a35c 100644
--- a/tests/testsuite/profile_targets.rs
+++ b/tests/testsuite/profile_targets.rs
@@ -1,4 +1,4 @@
-use crate::support::{basic_manifest, project, Project};
+use cargo_test_support::{basic_manifest, project, Project};
 
 // These tests try to exercise exactly which profiles are selected for every target.
 
diff --git a/tests/testsuite/profiles.rs b/tests/testsuite/profiles.rs
index ad7c5c63b2c..4fbbefa120c 100644
--- a/tests/testsuite/profiles.rs
+++ b/tests/testsuite/profiles.rs
@@ -1,6 +1,6 @@
 use std::env;
 
-use crate::support::project;
+use cargo_test_support::project;
 
 #[cargo_test]
 fn profile_overrides() {
diff --git a/tests/testsuite/pub_priv.rs b/tests/testsuite/pub_priv.rs
index 4a9f53ef2c9..d17e2365294 100644
--- a/tests/testsuite/pub_priv.rs
+++ b/tests/testsuite/pub_priv.rs
@@ -1,5 +1,5 @@
-use crate::support::registry::Package;
-use crate::support::{is_nightly, project};
+use cargo_test_support::registry::Package;
+use cargo_test_support::{is_nightly, project};
 
 #[cargo_test]
 fn exported_priv_warning() {
diff --git a/tests/testsuite/publish.rs b/tests/testsuite/publish.rs
index bb9c1edb752..e282796662b 100644
--- a/tests/testsuite/publish.rs
+++ b/tests/testsuite/publish.rs
@@ -1,10 +1,10 @@
 use std::fs::{self, File};
 use std::io::prelude::*;
 
-use crate::support::git::{self, repo};
-use crate::support::paths;
-use crate::support::registry::{self, registry_path, registry_url, Package};
-use crate::support::{basic_manifest, project, publish};
+use cargo_test_support::git::{self, repo};
+use cargo_test_support::paths;
+use cargo_test_support::registry::{self, registry_path, registry_url, Package};
+use cargo_test_support::{basic_manifest, project, publish};
 
 const CLEAN_FOO_JSON: &str = r#"
     {
diff --git a/tests/testsuite/publish_lockfile.rs b/tests/testsuite/publish_lockfile.rs
index 201e7959cb8..3daef142b27 100644
--- a/tests/testsuite/publish_lockfile.rs
+++ b/tests/testsuite/publish_lockfile.rs
@@ -1,8 +1,8 @@
 use std;
 use std::fs::File;
 
-use crate::support::registry::Package;
-use crate::support::{
+use cargo_test_support::registry::Package;
+use cargo_test_support::{
     basic_manifest, cargo_process, git, paths, project, publish::validate_crate_contents,
 };
 
diff --git a/tests/testsuite/read_manifest.rs b/tests/testsuite/read_manifest.rs
index b72060f3faf..33f86c6eee8 100644
--- a/tests/testsuite/read_manifest.rs
+++ b/tests/testsuite/read_manifest.rs
@@ -1,4 +1,4 @@
-use crate::support::{basic_bin_manifest, main_file, project};
+use cargo_test_support::{basic_bin_manifest, main_file, project};
 
 static MANIFEST_OUTPUT: &str = r#"
 {
diff --git a/tests/testsuite/registry.rs b/tests/testsuite/registry.rs
index 2db759ac1e2..b4de94e21e3 100644
--- a/tests/testsuite/registry.rs
+++ b/tests/testsuite/registry.rs
@@ -2,12 +2,12 @@ use std::fs::{self, File};
 use std::io::prelude::*;
 use std::path::Path;
 
-use crate::support::cargo_process;
-use crate::support::git;
-use crate::support::paths::{self, CargoPathExt};
-use crate::support::registry::{self, registry_path, registry_url, Dependency, Package};
-use crate::support::{basic_manifest, project};
 use cargo::util::paths::remove_dir_all;
+use cargo_test_support::cargo_process;
+use cargo_test_support::git;
+use cargo_test_support::paths::{self, CargoPathExt};
+use cargo_test_support::registry::{self, registry_path, registry_url, Dependency, Package};
+use cargo_test_support::{basic_manifest, project, t};
 
 #[cargo_test]
 fn simple() {
diff --git a/tests/testsuite/rename_deps.rs b/tests/testsuite/rename_deps.rs
index e94ac67eec7..ade3867d36c 100644
--- a/tests/testsuite/rename_deps.rs
+++ b/tests/testsuite/rename_deps.rs
@@ -1,7 +1,7 @@
-use crate::support::git;
-use crate::support::paths;
-use crate::support::registry::Package;
-use crate::support::{basic_manifest, project};
+use cargo_test_support::git;
+use cargo_test_support::paths;
+use cargo_test_support::registry::Package;
+use cargo_test_support::{basic_manifest, project};
 
 #[cargo_test]
 fn rename_dependency() {
diff --git a/tests/testsuite/required_features.rs b/tests/testsuite/required_features.rs
index 1e82b0fda71..fd3d72c676c 100644
--- a/tests/testsuite/required_features.rs
+++ b/tests/testsuite/required_features.rs
@@ -1,6 +1,8 @@
-use crate::support::install::{assert_has_installed_exe, assert_has_not_installed_exe, cargo_home};
-use crate::support::is_nightly;
-use crate::support::project;
+use cargo_test_support::install::{
+    assert_has_installed_exe, assert_has_not_installed_exe, cargo_home,
+};
+use cargo_test_support::is_nightly;
+use cargo_test_support::project;
 
 #[cargo_test]
 fn build_bin_default_features() {
diff --git a/tests/testsuite/resolve.rs b/tests/testsuite/resolve.rs
index ae428d9a99f..f20008ecf0a 100644
--- a/tests/testsuite/resolve.rs
+++ b/tests/testsuite/resolve.rs
@@ -1,5 +1,5 @@
-use crate::support::project;
-use crate::support::registry::Package;
+use cargo_test_support::project;
+use cargo_test_support::registry::Package;
 
 // Ensure that the "-Z minimal-versions" CLI option works and the minimal
 // version of a dependency ends up in the lock file.
diff --git a/tests/testsuite/run.rs b/tests/testsuite/run.rs
index 04afa8fc244..959873edf66 100644
--- a/tests/testsuite/run.rs
+++ b/tests/testsuite/run.rs
@@ -1,5 +1,5 @@
-use crate::support::{basic_bin_manifest, basic_lib_manifest, project, Project};
 use cargo::util::paths::dylib_path_envvar;
+use cargo_test_support::{basic_bin_manifest, basic_lib_manifest, project, Project};
 
 #[cargo_test]
 fn simple() {
@@ -1071,7 +1071,7 @@ fn default_run_workspace() {
 #[cargo_test]
 #[cfg(target_os = "macos")]
 fn run_link_system_path_macos() {
-    use crate::support::paths::{self, CargoPathExt};
+    use cargo_test_support::paths::{self, CargoPathExt};
     use std::fs;
     // Check that the default system library path is honored.
     // First, build a shared library that will be accessed from
diff --git a/tests/testsuite/rustc.rs b/tests/testsuite/rustc.rs
index 9fb3ad240cc..4af6dfe675b 100644
--- a/tests/testsuite/rustc.rs
+++ b/tests/testsuite/rustc.rs
@@ -1,4 +1,4 @@
-use crate::support::{basic_bin_manifest, basic_lib_manifest, basic_manifest, project};
+use cargo_test_support::{basic_bin_manifest, basic_lib_manifest, basic_manifest, project};
 
 const CARGO_RUSTC_ERROR: &str =
     "[ERROR] extra arguments to `rustc` can only be passed to one target, consider filtering
diff --git a/tests/testsuite/rustc_info_cache.rs b/tests/testsuite/rustc_info_cache.rs
index ceed53ee3a8..39a6d769328 100644
--- a/tests/testsuite/rustc_info_cache.rs
+++ b/tests/testsuite/rustc_info_cache.rs
@@ -1,11 +1,11 @@
-use crate::support::paths::CargoPathExt;
-use crate::support::{basic_manifest, project};
+use cargo_test_support::paths::CargoPathExt;
+use cargo_test_support::{basic_manifest, project};
 use std::env;
 
 #[cargo_test]
 fn rustc_info_cache() {
     // FIXME: when pipelining rides to stable, enable this test on all channels.
-    if !crate::support::is_nightly() {
+    if !cargo_test_support::is_nightly() {
         return;
     }
 
diff --git a/tests/testsuite/rustdoc.rs b/tests/testsuite/rustdoc.rs
index 50e613eeb0b..fd8ba61476d 100644
--- a/tests/testsuite/rustdoc.rs
+++ b/tests/testsuite/rustdoc.rs
@@ -1,4 +1,4 @@
-use crate::support::{basic_manifest, is_nightly, project};
+use cargo_test_support::{basic_manifest, is_nightly, project};
 
 #[cargo_test]
 fn rustdoc_simple() {
diff --git a/tests/testsuite/rustdocflags.rs b/tests/testsuite/rustdocflags.rs
index cc8a8730af9..7cfb220c851 100644
--- a/tests/testsuite/rustdocflags.rs
+++ b/tests/testsuite/rustdocflags.rs
@@ -1,4 +1,4 @@
-use crate::support::project;
+use cargo_test_support::project;
 
 #[cargo_test]
 fn parses_env() {
diff --git a/tests/testsuite/rustflags.rs b/tests/testsuite/rustflags.rs
index 0589b49accc..47221bd2a1c 100644
--- a/tests/testsuite/rustflags.rs
+++ b/tests/testsuite/rustflags.rs
@@ -1,8 +1,8 @@
 use std::fs::{self, File};
 use std::io::Write;
 
-use crate::support::registry::Package;
-use crate::support::{
+use cargo_test_support::registry::Package;
+use cargo_test_support::{
     basic_lib_manifest, basic_manifest, paths, project, project_in_home, rustc_host,
 };
 
diff --git a/tests/testsuite/search.rs b/tests/testsuite/search.rs
index 8cd0d7a107d..cc464cc7b18 100644
--- a/tests/testsuite/search.rs
+++ b/tests/testsuite/search.rs
@@ -3,10 +3,10 @@ use std::fs::{self, File};
 use std::io::prelude::*;
 use std::path::Path;
 
-use crate::support::cargo_process;
-use crate::support::git::repo;
-use crate::support::paths;
-use crate::support::registry::{api_path, registry_path, registry_url};
+use cargo_test_support::cargo_process;
+use cargo_test_support::git::repo;
+use cargo_test_support::paths;
+use cargo_test_support::registry::{api_path, registry_path, registry_url};
 use url::Url;
 
 fn api() -> Url {
diff --git a/tests/testsuite/shell_quoting.rs b/tests/testsuite/shell_quoting.rs
index 410f95b365c..50d58d559ff 100644
--- a/tests/testsuite/shell_quoting.rs
+++ b/tests/testsuite/shell_quoting.rs
@@ -2,7 +2,7 @@
 //! in the output, their arguments are quoted properly
 //! so that the command can be run in a terminal
 
-use crate::support::project;
+use cargo_test_support::project;
 
 #[cargo_test]
 fn features_are_quoted() {
diff --git a/tests/testsuite/small_fd_limits.rs b/tests/testsuite/small_fd_limits.rs
index f0ca6988e32..2a468e588b8 100644
--- a/tests/testsuite/small_fd_limits.rs
+++ b/tests/testsuite/small_fd_limits.rs
@@ -3,10 +3,10 @@ use std::ffi::OsStr;
 use std::path::PathBuf;
 use std::process::Command;
 
-use crate::support::git;
-use crate::support::paths;
-use crate::support::project;
-use crate::support::registry::Package;
+use cargo_test_support::git;
+use cargo_test_support::paths;
+use cargo_test_support::project;
+use cargo_test_support::registry::Package;
 use git2;
 
 use url::Url;
diff --git a/tests/testsuite/standard_lib.rs b/tests/testsuite/standard_lib.rs
index 0ca7856d979..80db0fcee20 100644
--- a/tests/testsuite/standard_lib.rs
+++ b/tests/testsuite/standard_lib.rs
@@ -1,283 +1,395 @@
-use crate::support::{is_nightly, paths, project, rustc_host, Execs, Project};
+use cargo_test_support::registry::{Dependency, Package};
+use cargo_test_support::{is_nightly, paths, project, rustc_host, Execs};
 
-fn cargo_build_std(project: &Project, cmd: &str, crates: &str) -> Execs {
-    let unstable = if crates.is_empty() {
-        "-Zbuild-std".to_string()
-    } else {
-        format!("-Zbuild-std={}", crates)
+fn setup() -> bool {
+    if !is_nightly() {
+        // -Zbuild-std is nightly
+        // We don't want these tests to run on rust-lang/rust.
+        return false;
+    }
+
+    // Our mock sysroot requires a few packages from crates.io, so make sure
+    // they're "published" to crates.io. Also edit their code a bit to make sure
+    // that they have access to our custom crates with custom apis.
+    Package::new("registry-dep-using-core", "1.0.0")
+        .file(
+            "src/lib.rs",
+            "
+                #![no_std]
+
+                #[cfg(feature = \"mockbuild\")]
+                pub fn custom_api() {
+                    core::custom_api();
+                }
+
+                #[cfg(not(feature = \"mockbuild\"))]
+                pub fn non_sysroot_api() {
+                    core::custom_api();
+                }
+            ",
+        )
+        .add_dep(Dependency::new("rustc-std-workspace-core", "*").optional(true))
+        .feature("mockbuild", &["rustc-std-workspace-core"])
+        .publish();
+    Package::new("registry-dep-using-alloc", "1.0.0")
+        .file(
+            "src/lib.rs",
+            "
+                #![no_std]
+
+                extern crate alloc;
+
+                #[cfg(feature = \"mockbuild\")]
+                pub fn custom_api() {
+                    core::custom_api();
+                    alloc::custom_api();
+                }
+
+                #[cfg(not(feature = \"mockbuild\"))]
+                pub fn non_sysroot_api() {
+                    core::custom_api();
+                    alloc::custom_api();
+                }
+            ",
+        )
+        .add_dep(Dependency::new("rustc-std-workspace-core", "*").optional(true))
+        .add_dep(Dependency::new("rustc-std-workspace-alloc", "*").optional(true))
+        .feature(
+            "mockbuild",
+            &["rustc-std-workspace-core", "rustc-std-workspace-alloc"],
+        )
+        .publish();
+    Package::new("registry-dep-using-std", "1.0.0")
+        .file(
+            "src/lib.rs",
+            "
+                #[cfg(feature = \"mockbuild\")]
+                pub fn custom_api() {
+                    std::custom_api();
+                }
+
+                #[cfg(not(feature = \"mockbuild\"))]
+                pub fn non_sysroot_api() {
+                    std::custom_api();
+                }
+            ",
+        )
+        .add_dep(Dependency::new("rustc-std-workspace-std", "*").optional(true))
+        .feature("mockbuild", &["rustc-std-workspace-std"])
+        .publish();
+    return true;
+}
+
+fn enable_build_std(e: &mut Execs, arg: Option<&str>) {
+    // First up, force Cargo to use our "mock sysroot" which mimics what
+    // libstd looks like upstream.
+    let root = paths::root();
+    let root = root
+        .parent() // chop off test name
+        .unwrap()
+        .parent() // chop off `citN`
+        .unwrap()
+        .parent() // chop off `target`
+        .unwrap()
+        .join("tests/testsuite/mock-std");
+    e.env("__CARGO_TESTS_ONLY_SRC_ROOT", &root);
+
+    // Next, make sure it doesn't have implicit access to the host's sysroot
+    e.env("RUSTFLAGS", "--sysroot=/path/to/nowhere");
+
+    // And finally actually enable `build-std` for now
+    let arg = match arg {
+        Some(s) => format!("-Zbuild-std={}", s),
+        None => "-Zbuild-std".to_string(),
     };
-    let target = paths::root().join("target");
-    let mut execs = project.cargo(cmd);
-    if !cmd.contains("--target") {
-        execs.arg("--target").arg(rustc_host());
+    e.arg(arg);
+    e.masquerade_as_nightly_cargo();
+}
+
+// Helper methods used in the tests below
+trait BuildStd: Sized {
+    fn build_std(&mut self) -> &mut Self;
+    fn build_std_arg(&mut self, arg: &str) -> &mut Self;
+    fn target_host(&mut self) -> &mut Self;
+}
+
+impl BuildStd for Execs {
+    fn build_std(&mut self) -> &mut Self {
+        enable_build_std(self, None);
+        self
+    }
+
+    fn build_std_arg(&mut self, arg: &str) -> &mut Self {
+        enable_build_std(self, Some(arg));
+        self
+    }
+
+    fn target_host(&mut self) -> &mut Self {
+        self.arg("--target").arg(rustc_host());
+        self
     }
-    execs
-        .arg(unstable)
-        .arg("-Zno-index-update")
-        .env_remove("CARGO_HOME")
-        .env_remove("HOME")
-        .env("CARGO_TARGET_DIR", target.as_os_str())
-        .masquerade_as_nightly_cargo();
-    execs
 }
 
 #[cargo_test]
-fn std_lib() {
-    if !is_nightly() {
-        // -Zbuild-std is nightly
-        // -Zno-index-update is nightly
-        // We don't want these tests to run on rust-lang/rust.
+fn basic() {
+    if !setup() {
         return;
     }
-    simple_lib_std();
-    simple_bin_std();
-    lib_nostd();
-    check_core();
-    cross_custom();
-    hashbrown();
-    libc();
-    test();
-    custom_test_framework();
-    target_proc_macro();
-    bench();
-    doc();
-    check_std();
-    doctest();
+
+    let p = project()
+        .file(
+            "src/main.rs",
+            "
+                fn main() {
+                    std::custom_api();
+                    foo::f();
+                }
+
+                #[test]
+                fn smoke_bin_unit() {
+                    std::custom_api();
+                    foo::f();
+                }
+            ",
+        )
+        .file(
+            "src/lib.rs",
+            "
+                extern crate alloc;
+                extern crate proc_macro;
+
+                /// ```
+                /// foo::f();
+                /// ```
+                pub fn f() {
+                    core::custom_api();
+                    std::custom_api();
+                    alloc::custom_api();
+                    proc_macro::custom_api();
+                }
+
+                #[test]
+                fn smoke_lib_unit() {
+                    std::custom_api();
+                    f();
+                }
+            ",
+        )
+        .file(
+            "tests/smoke.rs",
+            "
+                #[test]
+                fn smoke_integration() {
+                    std::custom_api();
+                    foo::f();
+                }
+            ",
+        )
+        .build();
+
+    p.cargo("check").build_std().target_host().run();
+    p.cargo("build").build_std().target_host().run();
+    p.cargo("run").build_std().target_host().run();
+    p.cargo("test").build_std().target_host().run();
 }
 
+#[cargo_test]
 fn simple_lib_std() {
+    if !setup() {
+        return;
+    }
     let p = project().file("src/lib.rs", "").build();
-    cargo_build_std(&p, "build -v", "")
+    p.cargo("build -v")
+        .build_std()
+        .target_host()
         .with_stderr_contains("[RUNNING] `rustc [..]--crate-name std [..]")
         .run();
     // Check freshness.
     p.change_file("src/lib.rs", " ");
-    cargo_build_std(&p, "build -v", "std")
+    p.cargo("build -v")
+        .build_std()
+        .target_host()
         .with_stderr_contains("[FRESH] std[..]")
         .run();
 }
 
+#[cargo_test]
 fn simple_bin_std() {
+    if !setup() {
+        return;
+    }
     let p = project().file("src/main.rs", "fn main() {}").build();
-    cargo_build_std(&p, "run -v", "std").run();
+    p.cargo("run -v").build_std().target_host().run();
 }
 
+#[cargo_test]
 fn lib_nostd() {
+    if !setup() {
+        return;
+    }
     let p = project()
         .file(
             "src/lib.rs",
             r#"
-            #![no_std]
-            pub fn foo() {
-                assert_eq!(core::u8::MIN, 0);
-            }
+                #![no_std]
+                pub fn foo() {
+                    assert_eq!(core::u8::MIN, 0);
+                }
             "#,
         )
         .build();
-    cargo_build_std(&p, "build -v --lib", "core")
+    p.cargo("build -v --lib")
+        .build_std_arg("core")
+        .target_host()
         .with_stderr_does_not_contain("[..]libstd[..]")
         .run();
 }
 
+#[cargo_test]
 fn check_core() {
+    if !setup() {
+        return;
+    }
     let p = project()
         .file("src/lib.rs", "#![no_std] fn unused_fn() {}")
         .build();
 
-    cargo_build_std(&p, "check -v", "core")
+    p.cargo("check -v")
+        .build_std_arg("core")
+        .target_host()
         .with_stderr_contains("[WARNING] [..]unused_fn[..]`")
         .run();
 }
 
-fn cross_custom() {
-    let p = project()
-        .file("src/lib.rs", "#![no_std] pub fn f() {}")
-        .file(
-            "custom-target.json",
-            r#"
-            {
-                "llvm-target": "x86_64-unknown-none-gnu",
-                "data-layout": "e-m:e-i64:64-f80:128-n8:16:32:64-S128",
-                "arch": "x86_64",
-                "target-endian": "little",
-                "target-pointer-width": "64",
-                "target-c-int-width": "32",
-                "os": "none",
-                "linker-flavor": "ld.lld"
-            }
-            "#,
-        )
-        .build();
-
-    cargo_build_std(&p, "build --target custom-target.json -v", "core").run();
-}
-
-fn hashbrown() {
-    let p = project()
-        .file(
-            "src/lib.rs",
-            r#"
-            pub fn f() -> hashbrown::HashMap<i32, i32> {
-                hashbrown::HashMap::new()
-            }
-            "#,
-        )
-        .file(
-            "Cargo.toml",
-            r#"
-            [package]
-            name = "foo"
-            version = "0.1.0"
-            edition = "2018"
-
-            [dependencies]
-            hashbrown = "=0.4.0"
-            "#,
-        )
-        .build();
-
-    cargo_build_std(&p, "build -v", "std").run();
-}
+#[cargo_test]
+fn depend_same_as_std() {
+    if !setup() {
+        return;
+    }
 
-fn libc() {
     let p = project()
         .file(
             "src/lib.rs",
             r#"
-            pub fn f() -> ! {
-                unsafe { libc::exit(123); }
-            }
+                pub fn f() {
+                    registry_dep_using_core::non_sysroot_api();
+                    registry_dep_using_alloc::non_sysroot_api();
+                    registry_dep_using_std::non_sysroot_api();
+                }
             "#,
         )
         .file(
             "Cargo.toml",
             r#"
-            [package]
-            name = "foo"
-            version = "0.1.0"
-            edition = "2018"
-
-            [dependencies]
-            libc = "=0.2.54"
+                [package]
+                name = "foo"
+                version = "0.1.0"
+                edition = "2018"
+
+                [dependencies]
+                registry-dep-using-core = "1.0"
+                registry-dep-using-alloc = "1.0"
+                registry-dep-using-std = "1.0"
             "#,
         )
         .build();
 
-    cargo_build_std(&p, "build -v", "std").run();
+    p.cargo("build -v").build_std().target_host().run();
 }
 
+#[cargo_test]
 fn test() {
+    if !setup() {
+        return;
+    }
     let p = project()
         .file(
             "src/lib.rs",
             r#"
-            #[cfg(test)]
-            mod tests {
-                #[test]
-                fn it_works() {
-                    assert_eq!(2 + 2, 4);
+                #[cfg(test)]
+                mod tests {
+                    #[test]
+                    fn it_works() {
+                        assert_eq!(2 + 2, 4);
+                    }
                 }
-            }
             "#,
         )
         .build();
 
-    cargo_build_std(&p, "test -v", "std")
+    p.cargo("test -v")
+        .build_std()
+        .target_host()
         .with_stdout_contains("test tests::it_works ... ok")
         .run();
 }
 
-fn custom_test_framework() {
-    let p = project()
-        .file(
-            "src/lib.rs",
-            r#"
-            #![no_std]
-            #![cfg_attr(test, no_main)]
-            #![feature(custom_test_frameworks)]
-            #![test_runner(crate::test_runner)]
-
-            pub fn test_runner(_tests: &[&dyn Fn()]) {}
-
-            #[panic_handler]
-            fn panic(_info: &core::panic::PanicInfo) -> ! {
-                loop {}
-            }
-            "#,
-        )
-        .file(
-            "target.json",
-            r#"
-            {
-                "llvm-target": "x86_64-unknown-none-gnu",
-                "data-layout": "e-m:e-i64:64-f80:128-n8:16:32:64-S128",
-                "arch": "x86_64",
-                "target-endian": "little",
-                "target-pointer-width": "64",
-                "target-c-int-width": "32",
-                "os": "none",
-                "linker-flavor": "ld.lld",
-                "linker": "rust-lld",
-                "executables": true,
-                "panic-strategy": "abort"
-            }
-            "#,
-        )
-        .build();
-
-    cargo_build_std(&p, "test --target target.json --no-run -v", "core").run();
-}
-
+#[cargo_test]
 fn target_proc_macro() {
+    if !setup() {
+        return;
+    }
     let p = project()
         .file(
             "src/lib.rs",
             r#"
-            extern crate proc_macro;
-            pub fn f() {
-                let _ts = proc_macro::TokenStream::new();
-            }
+                extern crate proc_macro;
+                pub fn f() {
+                    let _ts = proc_macro::TokenStream::new();
+                }
             "#,
         )
         .build();
 
-    cargo_build_std(&p, "build -v", "std,proc_macro").run();
+    p.cargo("build -v").build_std().target_host().run();
 }
 
+#[cargo_test]
 fn bench() {
+    if !setup() {
+        return;
+    }
     let p = project()
         .file(
             "src/lib.rs",
             r#"
-            #![feature(test)]
-            extern crate test;
+                #![feature(test)]
+                extern crate test;
 
-            #[bench]
-            fn b1(b: &mut test::Bencher) {
-                b.iter(|| ())
-            }
+                #[bench]
+                fn b1(b: &mut test::Bencher) {
+                    b.iter(|| ())
+                }
             "#,
         )
         .build();
 
-    cargo_build_std(&p, "bench -v", "std").run();
+    p.cargo("bench -v").build_std().target_host().run();
 }
 
+#[cargo_test]
 fn doc() {
+    if !setup() {
+        return;
+    }
     let p = project()
         .file(
             "src/lib.rs",
             r#"
-            /// Doc
-            pub fn f() -> Result<(), ()> {Ok(())}
+                /// Doc
+                pub fn f() -> Result<(), ()> {Ok(())}
             "#,
         )
         .build();
 
-    cargo_build_std(&p, "doc -v", "std").run();
+    p.cargo("doc -v").build_std().target_host().run();
 }
 
+#[cargo_test]
 fn check_std() {
+    if !setup() {
+        return;
+    }
     let p = project()
         .file(
             "src/lib.rs",
@@ -292,31 +404,41 @@ fn check_std() {
         .file(
             "tests/t1.rs",
             r#"
-            #[test]
-            fn t1() {
-                assert_eq!(1, 2);
-            }
+                #[test]
+                fn t1() {
+                    assert_eq!(1, 2);
+                }
             "#,
         )
         .build();
 
-    cargo_build_std(&p, "check -v --all-targets", "std").run();
-    cargo_build_std(&p, "check -v --all-targets --profile=test", "std").run();
+    p.cargo("check -v --all-targets")
+        .build_std()
+        .target_host()
+        .run();
+    p.cargo("check -v --all-targets --profile=test")
+        .build_std()
+        .target_host()
+        .run();
 }
 
+#[cargo_test]
 fn doctest() {
+    if !setup() {
+        return;
+    }
     let p = project()
         .file(
             "src/lib.rs",
             r#"
-            /// Doc
-            /// ```
-            /// assert_eq!(1, 1);
-            /// ```
-            pub fn f() {}
+                /// Doc
+                /// ```
+                /// assert_eq!(1, 1);
+                /// ```
+                pub fn f() {}
             "#,
         )
         .build();
 
-    cargo_build_std(&p, "test --doc -v", "std").run();
+    p.cargo("test --doc -v").build_std().target_host().run();
 }
diff --git a/tests/testsuite/test.rs b/tests/testsuite/test.rs
index bfb6e0e11c5..c61924577b7 100644
--- a/tests/testsuite/test.rs
+++ b/tests/testsuite/test.rs
@@ -3,10 +3,12 @@ use std::io::prelude::*;
 
 use cargo;
 
-use crate::support::paths::CargoPathExt;
-use crate::support::registry::Package;
-use crate::support::{basic_bin_manifest, basic_lib_manifest, basic_manifest, cargo_exe, project};
-use crate::support::{rustc_host, sleep_ms};
+use cargo_test_support::paths::CargoPathExt;
+use cargo_test_support::registry::Package;
+use cargo_test_support::{
+    basic_bin_manifest, basic_lib_manifest, basic_manifest, cargo_exe, project,
+};
+use cargo_test_support::{rustc_host, sleep_ms};
 
 #[cargo_test]
 fn cargo_test_simple() {
diff --git a/tests/testsuite/tool_paths.rs b/tests/testsuite/tool_paths.rs
index 07dfa082999..a198176ab82 100644
--- a/tests/testsuite/tool_paths.rs
+++ b/tests/testsuite/tool_paths.rs
@@ -1,5 +1,5 @@
-use crate::support::rustc_host;
-use crate::support::{basic_lib_manifest, project};
+use cargo_test_support::rustc_host;
+use cargo_test_support::{basic_lib_manifest, project};
 
 #[cargo_test]
 fn pathless_tools() {
diff --git a/tests/testsuite/update.rs b/tests/testsuite/update.rs
index eaeb806138a..1f7a2ed594b 100644
--- a/tests/testsuite/update.rs
+++ b/tests/testsuite/update.rs
@@ -1,8 +1,8 @@
 use std::fs::File;
 use std::io::prelude::*;
 
-use crate::support::registry::Package;
-use crate::support::{basic_manifest, project};
+use cargo_test_support::registry::Package;
+use cargo_test_support::{basic_manifest, project};
 
 #[cargo_test]
 fn minor_update_two_places() {
diff --git a/tests/testsuite/vendor.rs b/tests/testsuite/vendor.rs
index 42dbcca2345..61f1d2452a5 100644
--- a/tests/testsuite/vendor.rs
+++ b/tests/testsuite/vendor.rs
@@ -1,6 +1,6 @@
-use crate::support::git;
-use crate::support::registry::Package;
-use crate::support::{basic_lib_manifest, project, Project};
+use cargo_test_support::git;
+use cargo_test_support::registry::Package;
+use cargo_test_support::{basic_lib_manifest, project, Project};
 
 #[cargo_test]
 fn vendor_simple() {
diff --git a/tests/testsuite/verify_project.rs b/tests/testsuite/verify_project.rs
index 0bebf359def..a9bdb909b6b 100644
--- a/tests/testsuite/verify_project.rs
+++ b/tests/testsuite/verify_project.rs
@@ -1,4 +1,4 @@
-use crate::support::{basic_bin_manifest, main_file, project};
+use cargo_test_support::{basic_bin_manifest, main_file, project};
 
 fn verify_project_success_output() -> String {
     r#"{"success":"true"}"#.into()
diff --git a/tests/testsuite/version.rs b/tests/testsuite/version.rs
index 7a04bde0405..0cb9fcc97b5 100644
--- a/tests/testsuite/version.rs
+++ b/tests/testsuite/version.rs
@@ -1,5 +1,5 @@
-use crate::support::project;
 use cargo;
+use cargo_test_support::project;
 
 #[cargo_test]
 fn simple() {
diff --git a/tests/testsuite/warn_on_failure.rs b/tests/testsuite/warn_on_failure.rs
index bf662d81a77..0688326fd0f 100644
--- a/tests/testsuite/warn_on_failure.rs
+++ b/tests/testsuite/warn_on_failure.rs
@@ -1,5 +1,5 @@
-use crate::support::registry::Package;
-use crate::support::{project, Project};
+use cargo_test_support::registry::Package;
+use cargo_test_support::{project, Project};
 
 static WARNING1: &str = "Hello! I'm a warning. :)";
 static WARNING2: &str = "And one more!";
diff --git a/tests/testsuite/workspaces.rs b/tests/testsuite/workspaces.rs
index 0ec72048032..a86955f908b 100644
--- a/tests/testsuite/workspaces.rs
+++ b/tests/testsuite/workspaces.rs
@@ -2,9 +2,9 @@ use std::env;
 use std::fs::{self, File};
 use std::io::{Read, Write};
 
-use crate::support::registry::Package;
-use crate::support::sleep_ms;
-use crate::support::{basic_lib_manifest, basic_manifest, git, project};
+use cargo_test_support::registry::Package;
+use cargo_test_support::{basic_lib_manifest, basic_manifest, git, project};
+use cargo_test_support::{sleep_ms, t};
 
 #[cargo_test]
 fn simple_explicit() {