diff --git a/Cargo.lock b/Cargo.lock
index 9749049d1..1da72242a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -428,6 +428,7 @@ dependencies = [
  "env_logger",
  "failure",
  "flate2",
+ "git2",
  "hmac 0.7.1",
  "http 0.1.21",
  "hyper 0.12.35",
@@ -1028,9 +1029,9 @@ checksum = "f6503fe142514ca4799d4c26297c4248239fe8838d827db6bd6065c6ed29a6ce"
 
 [[package]]
 name = "git2"
-version = "0.13.12"
+version = "0.13.25"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ca6f1a0238d7f8f8fd5ee642f4ebac4dbc03e03d1f78fbe7a3ede35dcf7e2224"
+checksum = "f29229cc1b24c0e6062f6e742aa3e256492a5323365e5ed3413599f8a5eff7d6"
 dependencies = [
  "bitflags",
  "libc",
@@ -1481,9 +1482,9 @@ checksum = "1b03d17f364a3a042d5e5d46b053bbbf82c92c9430c592dd4c064dc6ee997125"
 
 [[package]]
 name = "libgit2-sys"
-version = "0.12.14+1.1.0"
+version = "0.12.26+1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8f25af58e6495f7caf2919d08f212de550cfa3ed2f5e744988938ea292b9f549"
+checksum = "19e1c899248e606fbfe68dcb31d8b0176ebab833b103824af31bddf4b7457494"
 dependencies = [
  "cc",
  "libc",
diff --git a/Cargo.toml b/Cargo.toml
index 822657cc5..1990754b9 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -64,6 +64,7 @@ ctrlc = "3.1.3"
 prometheus = "0.7.0"
 cargo_metadata = "0.12.1"
 indexmap = "1.4.0"
+git2 = { version = "0.13", features = ["vendored-libgit2"] }
 
 [dev-dependencies]
 assert_cmd = "1.0.2"
diff --git a/config.toml b/config.toml
index df959f59d..06475de29 100644
--- a/config.toml
+++ b/config.toml
@@ -27,7 +27,8 @@ local-crates = []
 
 [sandbox]
 # Maximum amount of RAM allowed during builds
-memory-limit = "1536M"  # 1.5G
+memory-limit = "4096M"  # 4G, 1G/cpu
+cpu-limit = 4
 # Restrictions on the amount of information stored in build logs
 build-log-max-size = "5M"
 build-log-max-lines = 10000
diff --git a/src/config.rs b/src/config.rs
index ae637837b..d36d085b2 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -74,6 +74,7 @@ pub struct DemoCrates {
 #[serde(rename_all = "kebab-case")]
 pub struct SandboxConfig {
     pub memory_limit: Size,
+    pub cpu_limit: u16,
     pub build_log_max_size: Size,
     pub build_log_max_lines: usize,
 }
@@ -256,6 +257,7 @@ impl Default for Config {
             local_crates: HashMap::new(),
             sandbox: SandboxConfig {
                 memory_limit: Size::Gigabytes(2),
+                cpu_limit: 1,
                 build_log_max_size: Size::Megabytes(1),
                 build_log_max_lines: 1000,
             },
@@ -308,6 +310,7 @@ mod tests {
             "local-crates = []\n",
             "[sandbox]\n",
             "memory-limit = \"2G\"\n",
+            "cpu-limit = 1\n",
             "build-log-max-size = \"2M\"\n",
             "build-log-max-lines = 1000\n",
             "[crates]\n",
diff --git a/src/runner/test.rs b/src/runner/test.rs
index f1473095d..de31e914e 100644
--- a/src/runner/test.rs
+++ b/src/runner/test.rs
@@ -89,6 +89,9 @@ fn run_cargo<DB: WriteResults>(
         rustflags.push(' ');
         rustflags.push_str(tc_rustflags);
     }
+    // Limit debuginfo in an effort to decrease linker peak memory usage, while retaining enough
+    // information to get useful backtraces.
+    rustflags.push_str(" -Cdebuginfo=1");
 
     let rustflags_env = if let Some(&"doc") = args.get(0) {
         "RUSTDOCFLAGS"
@@ -210,6 +213,7 @@ pub(super) fn run_test<DB: WriteResults>(
                 );
                 let sandbox = SandboxBuilder::new()
                     .memory_limit(Some(ctx.config.sandbox.memory_limit.to_bytes()))
+                    .cpu_limit(Some(f32::from(ctx.config.sandbox.cpu_limit)))
                     .enable_networking(false);
 
                 let krate = &ctx.krate.to_rustwide();
@@ -235,17 +239,31 @@ fn build<DB: WriteResults>(
     build_env: &Build,
     local_packages_id: &HashSet<PackageId>,
 ) -> Fallible<()> {
+    let cpus = ctx.config.sandbox.cpu_limit.to_string();
     run_cargo(
         ctx,
         build_env,
-        &["build", "--frozen", "--message-format=json"],
+        &[
+            "build",
+            "--frozen",
+            "--message-format=json",
+            "--jobs",
+            &cpus,
+        ],
         true,
         local_packages_id,
     )?;
     run_cargo(
         ctx,
         build_env,
-        &["test", "--frozen", "--no-run", "--message-format=json"],
+        &[
+            "test",
+            "--frozen",
+            "--no-run",
+            "--message-format=json",
+            "--jobs",
+            &cpus,
+        ],
         true,
         local_packages_id,
     )?;
@@ -253,10 +271,19 @@ fn build<DB: WriteResults>(
 }
 
 fn test<DB: WriteResults>(ctx: &TaskCtx<DB>, build_env: &Build) -> Fallible<()> {
+    let cpus = ctx.config.sandbox.cpu_limit.to_string();
     run_cargo(
         ctx,
         build_env,
-        &["test", "--frozen"],
+        &[
+            "test",
+            "--frozen",
+            "--jobs",
+            &cpus,
+            "--",
+            "--test-threads",
+            &cpus,
+        ],
         false,
         &HashSet::new(),
     )
@@ -299,6 +326,7 @@ pub(super) fn test_check_only<DB: WriteResults>(
     build_env: &Build,
     local_packages_id: &HashSet<PackageId>,
 ) -> Fallible<TestResult> {
+    let cpus = ctx.config.sandbox.cpu_limit.to_string();
     if let Err(err) = run_cargo(
         ctx,
         build_env,
@@ -308,6 +336,8 @@ pub(super) fn test_check_only<DB: WriteResults>(
             "--all",
             "--all-targets",
             "--message-format=json",
+            "--jobs",
+            &cpus,
         ],
         true,
         local_packages_id,
@@ -323,6 +353,7 @@ pub(super) fn test_clippy_only<DB: WriteResults>(
     build_env: &Build,
     local_packages_id: &HashSet<PackageId>,
 ) -> Fallible<TestResult> {
+    let cpus = ctx.config.sandbox.cpu_limit.to_string();
     if let Err(err) = run_cargo(
         ctx,
         build_env,
@@ -332,6 +363,8 @@ pub(super) fn test_clippy_only<DB: WriteResults>(
             "--all",
             "--all-targets",
             "--message-format=json",
+            "--jobs",
+            &cpus,
         ],
         true,
         local_packages_id,
@@ -347,6 +380,7 @@ pub(super) fn test_rustdoc<DB: WriteResults>(
     build_env: &Build,
     local_packages_id: &HashSet<PackageId>,
 ) -> Fallible<TestResult> {
+    let cpus = ctx.config.sandbox.cpu_limit.to_string();
     let res = run_cargo(
         ctx,
         build_env,
@@ -356,6 +390,8 @@ pub(super) fn test_rustdoc<DB: WriteResults>(
             "--no-deps",
             "--document-private-items",
             "--message-format=json",
+            "--jobs",
+            &cpus,
         ],
         true,
         local_packages_id,
diff --git a/tests/check_config/bad-duplicate-crate.toml b/tests/check_config/bad-duplicate-crate.toml
index f4e438e0d..b2e553750 100644
--- a/tests/check_config/bad-duplicate-crate.toml
+++ b/tests/check_config/bad-duplicate-crate.toml
@@ -17,6 +17,7 @@ local-crates = []
 
 [sandbox]
 memory-limit = "1536M"
+cpu-limit = 1
 build-log-max-size = "2M"
 build-log-max-lines = 1000
 
diff --git a/tests/check_config/bad-missing-crate.toml b/tests/check_config/bad-missing-crate.toml
index 3fff66502..d5d2f6d36 100644
--- a/tests/check_config/bad-missing-crate.toml
+++ b/tests/check_config/bad-missing-crate.toml
@@ -17,6 +17,7 @@ local-crates = []
 
 [sandbox]
 memory-limit = "1536M"
+cpu-limit = 1
 build-log-max-size = "2M"
 build-log-max-lines = 1000
 
diff --git a/tests/check_config/bad-missing-repo.toml b/tests/check_config/bad-missing-repo.toml
index 6b077bc3b..7477fee72 100644
--- a/tests/check_config/bad-missing-repo.toml
+++ b/tests/check_config/bad-missing-repo.toml
@@ -17,6 +17,7 @@ local-crates = []
 
 [sandbox]
 memory-limit = "1536M"
+cpu-limit= 1
 build-log-max-size = "2M"
 build-log-max-lines = 1000
 
diff --git a/tests/check_config/good.toml b/tests/check_config/good.toml
index 4f9903b27..1de068867 100644
--- a/tests/check_config/good.toml
+++ b/tests/check_config/good.toml
@@ -17,6 +17,7 @@ local-crates = []
 
 [sandbox]
 memory-limit = "1536M"
+cpu-limit = 1
 build-log-max-size = "2M"
 build-log-max-lines = 1000
 
diff --git a/tests/minicrater/blacklist/config.toml b/tests/minicrater/blacklist/config.toml
index 7a04174b8..a349ade06 100644
--- a/tests/minicrater/blacklist/config.toml
+++ b/tests/minicrater/blacklist/config.toml
@@ -18,6 +18,7 @@ local-crates = ["build-pass", "build-fail", "test-fail"]
 
 [sandbox]
 memory-limit = "512M"
+cpu-limit = 1
 build-log-max-size = "2M"
 build-log-max-lines = 1000
 
diff --git a/tests/minicrater/clippy/config.toml b/tests/minicrater/clippy/config.toml
index c64180af7..6ec5404fd 100644
--- a/tests/minicrater/clippy/config.toml
+++ b/tests/minicrater/clippy/config.toml
@@ -17,6 +17,7 @@ local-crates = ["build-pass", "clippy-warn"]
 
 [sandbox]
 memory-limit = "512M"
+cpu-limit = 1
 build-log-max-size = "2M"
 build-log-max-lines = 1000
 
diff --git a/tests/minicrater/full/config.toml b/tests/minicrater/full/config.toml
index b138311b9..f23f1763b 100644
--- a/tests/minicrater/full/config.toml
+++ b/tests/minicrater/full/config.toml
@@ -17,6 +17,7 @@ local-crates = []
 
 [sandbox]
 memory-limit = "512M"
+cpu-limit = 1
 build-log-max-size = "2M"
 build-log-max-lines = 1000
 
diff --git a/tests/minicrater/ignore-blacklist/config.toml b/tests/minicrater/ignore-blacklist/config.toml
index 973f0be1b..2d96b5b90 100644
--- a/tests/minicrater/ignore-blacklist/config.toml
+++ b/tests/minicrater/ignore-blacklist/config.toml
@@ -17,6 +17,7 @@ local-crates = ["build-pass", "build-fail", "test-fail"]
 
 [sandbox]
 memory-limit = "512M"
+cpu-limit = 1
 build-log-max-size = "2M"
 build-log-max-lines = 1000
 
diff --git a/tests/minicrater/missing-repo/config.toml b/tests/minicrater/missing-repo/config.toml
index 7f509facc..407f36266 100644
--- a/tests/minicrater/missing-repo/config.toml
+++ b/tests/minicrater/missing-repo/config.toml
@@ -17,6 +17,7 @@ local-crates = []
 
 [sandbox]
 memory-limit = "512M"
+cpu-limit = 1
 build-log-max-size = "2M"
 build-log-max-lines = 1000
 
diff --git a/tests/minicrater/resource-exhaustion/config.toml b/tests/minicrater/resource-exhaustion/config.toml
index e74994989..799c127e7 100644
--- a/tests/minicrater/resource-exhaustion/config.toml
+++ b/tests/minicrater/resource-exhaustion/config.toml
@@ -17,6 +17,7 @@ local-crates = ["build-pass", "memory-hungry"]
 
 [sandbox]
 memory-limit = "512M"
+cpu-limit = 1
 build-log-max-size = "2M"
 build-log-max-lines = 1000
 
diff --git a/tests/minicrater/small/config.toml b/tests/minicrater/small/config.toml
index fcedc7cfb..98f5160b4 100644
--- a/tests/minicrater/small/config.toml
+++ b/tests/minicrater/small/config.toml
@@ -17,6 +17,7 @@ local-crates = ["build-pass", "beta-regression"]
 
 [sandbox]
 memory-limit = "512M"
+cpu-limit = 1
 build-log-max-size = "2M"
 build-log-max-lines = 1000