diff --git a/Cargo.toml b/Cargo.toml
index 4a2a71ba860..9c0250f1930 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -9,6 +9,5 @@ members = [
 
   # Internal
   "examples",
-  "tests-build",
   "tests-integration",
 ]
diff --git a/azure-pipelines.yml b/azure-pipelines.yml
index ae2bd1bb145..e60090f7eea 100644
--- a/azure-pipelines.yml
+++ b/azure-pipelines.yml
@@ -25,20 +25,8 @@ jobs:
     displayName: Test tokio
     cross: true
     crates:
-      tokio:
-        - fs
-        - io
-        - io-util
-        - net-driver
-        - process
-        - rt-full
-        - signal
-        - sync
-        - tcp
-        - timer
-        - udp
-        - uds
-      tests-integration: []
+      - tokio
+      - tests-integration
 
 # Test crates that are NOT platform specific
 - template: ci/azure-test-stable.yml
@@ -47,29 +35,10 @@ jobs:
     displayName: Test sub crates -
     rust: beta
     crates:
-      tokio-macros: []
-      tokio-test: []
-      tokio-util: []
-      examples: []
-
-# Test compilation failure
-# Disable pending: https://github.com/tokio-rs/tokio/pull/1695#issuecomment-547045383
-# - template: ci/azure-test-stable.yml
-#   parameters:
-#     name: test_features
-#     displayName: Test feature flags
-#     rust: beta
-#     crates:
-#       tests-build:
-#         # - tokio-executor
-#         # - executor-without-current-thread
-#         # - macros-invalid-input
-#         # - net-no-features
-#         # - net-with-tcp
-#         # - net-with-udp
-#         # - net-with-uds
-#         # - tokio-no-features
-#         # - tokio-with-net
+      - tokio-macros
+      - tokio-test
+      - tokio-util
+      - examples
 
 # Run loom tests
 - template: ci/azure-loom.yml
diff --git a/ci/azure-test-stable.yml b/ci/azure-test-stable.yml
index f0ff7a7c19a..93e9ee1383a 100644
--- a/ci/azure-test-stable.yml
+++ b/ci/azure-test-stable.yml
@@ -20,6 +20,11 @@ jobs:
       # rust_version: stable
       rust_version: ${{ parameters.rust }}
 
+  - script: cargo install cargo-hack
+    displayName: Install cargo-hack
+    # FIXME(taiki-e): many features of current cargo-hack are not available on windows: https://github.com/taiki-e/cargo-hack/issues/3
+    condition: not(eq(variables['Agent.OS'], 'Windows_NT'))
+
   - template: azure-is-release.yml
 
   - ${{ each crate in parameters.crates }}:
@@ -28,17 +33,28 @@ jobs:
       env:
         LOOM_MAX_PREEMPTIONS: 2
         CI: 'True'
-      displayName: ${{ crate.key }} - cargo test
-      workingDirectory: $(Build.SourcesDirectory)/${{ crate.key }}
-
-    # Run with each specified feature
-    - ${{ each feature in crate.value }}:
-      - script: cargo test --no-default-features --features ${{ feature }}
-        env:
-          LOOM_MAX_PREEMPTIONS: 2
-          CI: 'True'
-        displayName: ${{ crate.key }} - cargo test --features ${{ feature }}
-        workingDirectory: $(Build.SourcesDirectory)/${{ crate.key }}
+      displayName: ${{ crate }} - cargo test
+      workingDirectory: $(Build.SourcesDirectory)/${{ crate }}
+
+    # Run with all crate features
+    - script: cargo test --all-features
+      env:
+        LOOM_MAX_PREEMPTIONS: 2
+        CI: 'True'
+      displayName: ${{ crate }} - cargo test --all-features
+      workingDirectory: $(Build.SourcesDirectory)/${{ crate }}
+
+    # Check each specified feature works properly
+    # * --each-feature - run for each feature which includes --no-default-features and default features of package
+    # * --no-dev-deps - build without dev-dependencies to avoid https://github.com/rust-lang/cargo/issues/4866
+    - script: cargo hack check --each-feature --no-dev-deps
+      env:
+        LOOM_MAX_PREEMPTIONS: 2
+        CI: 'True'
+      displayName: ${{ crate }} - cargo hack check --each-feature
+      workingDirectory: $(Build.SourcesDirectory)/${{ crate }}
+      # FIXME(taiki-e): many features of current cargo-hack are not available on windows: https://github.com/taiki-e/cargo-hack/issues/3
+      condition: not(eq(variables['Agent.OS'], 'Windows_NT'))
 
   - template: azure-patch-crates.yml
 
@@ -48,14 +64,25 @@ jobs:
       env:
         LOOM_MAX_PREEMPTIONS: 2
         CI: 'True'
-      displayName: ${{ crate.key }} - cargo test
-      workingDirectory: $(Build.SourcesDirectory)/${{ crate.key }}
-
-    # Run with each specified feature
-    - ${{ each feature in crate.value }}:
-      - script: cargo test --no-default-features --features ${{ feature }}
-        env:
-          LOOM_MAX_PREEMPTIONS: 2
-          CI: 'True'
-        displayName: ${{ crate.key }} - cargo test --features ${{ feature }}
-        workingDirectory: $(Build.SourcesDirectory)/${{ crate.key }}
+      displayName: ${{ crate }} - cargo test
+      workingDirectory: $(Build.SourcesDirectory)/${{ crate }}
+
+    # Run with all crate features
+    - script: cargo test --all-features
+      env:
+        LOOM_MAX_PREEMPTIONS: 2
+        CI: 'True'
+      displayName: ${{ crate }} - cargo test --all-features
+      workingDirectory: $(Build.SourcesDirectory)/${{ crate }}
+
+    # Check each specified feature works properly
+    # * --each-feature - run for each feature which includes --no-default-features and default features of package
+    # * --no-dev-deps - build without dev-dependencies to avoid https://github.com/rust-lang/cargo/issues/4866
+    - script: cargo hack check --each-feature --no-dev-deps
+      env:
+        LOOM_MAX_PREEMPTIONS: 2
+        CI: 'True'
+      displayName: ${{ crate }} - cargo hack check --each-feature
+      workingDirectory: $(Build.SourcesDirectory)/${{ crate }}
+      # FIXME(taiki-e): many features of current cargo-hack are not available on windows: https://github.com/taiki-e/cargo-hack/issues/3
+      condition: not(eq(variables['Agent.OS'], 'Windows_NT'))
diff --git a/tests-build/Cargo.toml b/tests-build/Cargo.toml
deleted file mode 100644
index 36dbc883ca9..00000000000
--- a/tests-build/Cargo.toml
+++ /dev/null
@@ -1,25 +0,0 @@
-[package]
-name = "tests-build"
-version = "0.1.0"
-authors = ["Tokio Contributors <team@tokio.rs>"]
-edition = "2018"
-publish = false
-
-[features]
-# executor-without-current-thread = ["tokio-executor"]
-# macros-invalid-input = ["tokio/rt-full"]
-# net-no-features = ["tokio-net"]
-# net-with-tcp = ["tokio-net/tcp"]
-# net-with-udp = ["tokio-net/udp"]
-# net-with-uds = ["tokio-net/uds"]
-# net-with-process = ["tokio-net/process"]
-# tokio-no-features = ["tokio"]
-# tokio-with-net = ["tokio/net-full"]
-
-# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
-
-[dependencies]
-# tokio = { path = "../tokio", optional = true, default-features = false }
-
-[dev-dependencies]
-trybuild = "1.0"
diff --git a/tests-build/README.md b/tests-build/README.md
deleted file mode 100644
index f491e2bc377..00000000000
--- a/tests-build/README.md
+++ /dev/null
@@ -1,2 +0,0 @@
-Tests the various combination of feature flags. This is broken out to a separate
-crate to work around limitations with cargo features.
diff --git a/tests-build/src/lib.rs b/tests-build/src/lib.rs
deleted file mode 100644
index 7f38a440600..00000000000
--- a/tests-build/src/lib.rs
+++ /dev/null
@@ -1,8 +0,0 @@
-#[cfg(feature = "tokio-executor")]
-pub use tokio_executor;
-
-#[cfg(feature = "tokio-net")]
-pub use tokio_net;
-
-#[cfg(feature = "tokio")]
-pub use tokio;
diff --git a/tests-build/tests/fail/executor_without_current_thread.rs b/tests-build/tests/fail/executor_without_current_thread.rs
deleted file mode 100644
index 205ce7e42be..00000000000
--- a/tests-build/tests/fail/executor_without_current_thread.rs
+++ /dev/null
@@ -1,3 +0,0 @@
-use tests_build::tokio_executor::current_thread;
-
-fn main() {}
diff --git a/tests-build/tests/fail/executor_without_current_thread.stderr b/tests-build/tests/fail/executor_without_current_thread.stderr
deleted file mode 100644
index f2287c3fcdd..00000000000
--- a/tests-build/tests/fail/executor_without_current_thread.stderr
+++ /dev/null
@@ -1,7 +0,0 @@
-error[E0432]: unresolved import `tests_build::tokio_executor::current_thread`
- --> $DIR/executor_without_current_thread.rs:1:5
-  |
-1 | use tests_build::tokio_executor::current_thread;
-  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ no `current_thread` in `tokio_executor`
-
-For more information about this error, try `rustc --explain E0432`.
diff --git a/tests-build/tests/fail/macros_invalid_input.rs b/tests-build/tests/fail/macros_invalid_input.rs
deleted file mode 100644
index 5b1a8adc075..00000000000
--- a/tests-build/tests/fail/macros_invalid_input.rs
+++ /dev/null
@@ -1,25 +0,0 @@
-use tests_build::tokio;
-
-#[tokio::main]
-fn main_is_not_async() {}
-
-#[tokio::main(foo)]
-async fn main_attr_has_unknown_args() {}
-
-#[tokio::main(threadpool::bar)]
-async fn main_attr_has_path_args() {}
-
-#[tokio::test]
-fn test_is_not_async() {}
-
-#[tokio::test]
-async fn test_fn_has_args(_x: u8) {}
-
-#[tokio::test(foo)]
-async fn test_attr_has_args() {}
-
-#[tokio::test]
-#[test]
-async fn test_has_second_test_attr() {}
-
-fn main() {}
diff --git a/tests-build/tests/fail/macros_invalid_input.stderr b/tests-build/tests/fail/macros_invalid_input.stderr
deleted file mode 100644
index 12373486485..00000000000
--- a/tests-build/tests/fail/macros_invalid_input.stderr
+++ /dev/null
@@ -1,41 +0,0 @@
-error: the async keyword is missing from the function declaration
- --> $DIR/macros_invalid_input.rs:4:1
-  |
-4 | fn main_is_not_async() {}
-  | ^^
-
-error: Unknown attribute foo is specified; expected `current_thread` or `threadpool`
- --> $DIR/macros_invalid_input.rs:6:15
-  |
-6 | #[tokio::main(foo)]
-  |               ^^^
-
-error: Must have specified ident
- --> $DIR/macros_invalid_input.rs:9:15
-  |
-9 | #[tokio::main(threadpool::bar)]
-  |               ^^^^^^^^^^^^^^^
-
-error: the async keyword is missing from the function declaration
-  --> $DIR/macros_invalid_input.rs:13:1
-   |
-13 | fn test_is_not_async() {}
-   | ^^
-
-error: the test function cannot accept arguments
-  --> $DIR/macros_invalid_input.rs:16:27
-   |
-16 | async fn test_fn_has_args(_x: u8) {}
-   |                           ^^^^^^
-
-error: Unknown attribute foo is specified; expected `current_thread` or `threadpool`
-  --> $DIR/macros_invalid_input.rs:18:15
-   |
-18 | #[tokio::test(foo)]
-   |               ^^^
-
-error: second test attribute is supplied
-  --> $DIR/macros_invalid_input.rs:22:1
-   |
-22 | #[test]
-   | ^^^^^^^
diff --git a/tests-build/tests/fail/net_without_tcp_missing_tcp.rs b/tests-build/tests/fail/net_without_tcp_missing_tcp.rs
deleted file mode 100644
index 80010233abb..00000000000
--- a/tests-build/tests/fail/net_without_tcp_missing_tcp.rs
+++ /dev/null
@@ -1,4 +0,0 @@
-use tests_build::tokio_net::tcp;
-
-fn main() {}
-
diff --git a/tests-build/tests/fail/net_without_tcp_missing_tcp.stderr b/tests-build/tests/fail/net_without_tcp_missing_tcp.stderr
deleted file mode 100644
index 83ff59fb4b3..00000000000
--- a/tests-build/tests/fail/net_without_tcp_missing_tcp.stderr
+++ /dev/null
@@ -1,7 +0,0 @@
-error[E0432]: unresolved import `tests_build::tokio_net::tcp`
- --> $DIR/net_without_tcp_missing_tcp.rs:1:5
-  |
-1 | use tests_build::tokio_net::tcp;
-  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^ no `tcp` in `tokio_net`
-
-For more information about this error, try `rustc --explain E0432`.
diff --git a/tests-build/tests/fail/net_without_udp_missing_udp.rs b/tests-build/tests/fail/net_without_udp_missing_udp.rs
deleted file mode 100644
index 6731af93f80..00000000000
--- a/tests-build/tests/fail/net_without_udp_missing_udp.rs
+++ /dev/null
@@ -1,4 +0,0 @@
-use tests_build::tokio_net::udp;
-
-fn main() {}
-
diff --git a/tests-build/tests/fail/net_without_udp_missing_udp.stderr b/tests-build/tests/fail/net_without_udp_missing_udp.stderr
deleted file mode 100644
index e3471a792ec..00000000000
--- a/tests-build/tests/fail/net_without_udp_missing_udp.stderr
+++ /dev/null
@@ -1,7 +0,0 @@
-error[E0432]: unresolved import `tests_build::tokio_net::udp`
- --> $DIR/net_without_udp_missing_udp.rs:1:5
-  |
-1 | use tests_build::tokio_net::udp;
-  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^ no `udp` in `tokio_net`
-
-For more information about this error, try `rustc --explain E0432`.
diff --git a/tests-build/tests/fail/net_without_uds_missing_uds.rs b/tests-build/tests/fail/net_without_uds_missing_uds.rs
deleted file mode 100644
index d48a5eb40e1..00000000000
--- a/tests-build/tests/fail/net_without_uds_missing_uds.rs
+++ /dev/null
@@ -1,4 +0,0 @@
-use tests_build::tokio_net::uds;
-
-fn main() {}
-
diff --git a/tests-build/tests/fail/net_without_uds_missing_uds.stderr b/tests-build/tests/fail/net_without_uds_missing_uds.stderr
deleted file mode 100644
index ad79fe1836a..00000000000
--- a/tests-build/tests/fail/net_without_uds_missing_uds.stderr
+++ /dev/null
@@ -1,7 +0,0 @@
-error[E0432]: unresolved import `tests_build::tokio_net::uds`
- --> $DIR/net_without_uds_missing_uds.rs:1:5
-  |
-1 | use tests_build::tokio_net::uds;
-  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^ no `uds` in `tokio_net`
-
-For more information about this error, try `rustc --explain E0432`.
diff --git a/tests-build/tests/fail/tokio_without_net_missing_net.rs b/tests-build/tests/fail/tokio_without_net_missing_net.rs
deleted file mode 100644
index f2e2783648c..00000000000
--- a/tests-build/tests/fail/tokio_without_net_missing_net.rs
+++ /dev/null
@@ -1,3 +0,0 @@
-use tests_build::tokio::net;
-
-fn main() {}
diff --git a/tests-build/tests/fail/tokio_without_net_missing_net.stderr b/tests-build/tests/fail/tokio_without_net_missing_net.stderr
deleted file mode 100644
index 4435b0a6607..00000000000
--- a/tests-build/tests/fail/tokio_without_net_missing_net.stderr
+++ /dev/null
@@ -1,7 +0,0 @@
-error[E0432]: unresolved import `tests_build::tokio::net`
- --> $DIR/tokio_without_net_missing_net.rs:1:5
-  |
-1 | use tests_build::tokio::net;
-  |     ^^^^^^^^^^^^^^^^^^^^^^^ no `net` in `tokio`
-
-For more information about this error, try `rustc --explain E0432`.
diff --git a/tests-build/tests/features.rs b/tests-build/tests/features.rs
deleted file mode 100644
index b40e44ed6ea..00000000000
--- a/tests-build/tests/features.rs
+++ /dev/null
@@ -1,62 +0,0 @@
-#![allow(unused_imports)]
-
-#[test]
-#[cfg(feature = "tokio-net")]
-fn net_default() {
-    use tests_build::tokio_net::driver::{set_default, Handle, Reactor, Registration};
-    use tests_build::tokio_net::util::PollEvented;
-}
-
-#[test]
-#[cfg(feature = "net-with-tcp")]
-fn net_with_tcp() {
-    use tests_build::tokio_net::tcp;
-}
-
-#[test]
-#[cfg(feature = "net-with-udp")]
-fn net_with_udp() {
-    use tests_build::tokio_net::udp;
-}
-
-#[test]
-#[cfg(feature = "net-with-uds")]
-fn net_with_uds() {
-    use tests_build::tokio_net::uds;
-}
-
-#[test]
-#[cfg(feature = "net-with-process")]
-fn net_with_process() {
-    use tests_build::tokio_net::process;
-}
-
-#[test]
-#[cfg(feature = "tokio-with-net")]
-fn tokio_with_net() {
-    // net is present
-    use tests_build::tokio::net;
-}
-
-#[test]
-fn compile_fail() {
-    let t = trybuild::TestCases::new();
-
-    #[cfg(feature = "executor-without-current-thread")]
-    t.compile_fail("tests/fail/executor_without_current_thread.rs");
-
-    #[cfg(feature = "macros-invalid-input")]
-    t.compile_fail("tests/fail/macros_invalid_input.rs");
-
-    #[cfg(feature = "net-no-features")]
-    {
-        t.compile_fail("tests/fail/net_without_tcp_missing_tcp.rs");
-        t.compile_fail("tests/fail/net_without_udp_missing_udp.rs");
-        t.compile_fail("tests/fail/net_without_uds_missing_uds.rs");
-    }
-
-    #[cfg(feature = "tokio-no-features")]
-    t.compile_fail("tests/fail/tokio_without_net_missing_net.rs");
-
-    drop(t);
-}
diff --git a/tokio/Cargo.toml b/tokio/Cargo.toml
index ee32b954aeb..18e371f81c9 100644
--- a/tokio/Cargo.toml
+++ b/tokio/Cargo.toml
@@ -36,19 +36,24 @@ default = [
   "timer",
 ]
 
-blocking = []
-fs = ["blocking"]
+executor-core = []
+blocking = ["executor-core", "sync"]
+fs = ["blocking", "io-traits"]
 io-traits = ["bytes", "iovec"]
 io-util = ["io-traits", "pin-project", "memchr"]
 io = ["io-traits", "io-util"]
 macros = ["tokio-macros"]
 net-full = ["tcp", "udp", "uds"]
-net-driver = ["mio", "blocking", "lazy_static"]
+net-driver = ["io-traits", "mio", "blocking", "lazy_static"]
 rt-current-thread = [
+  "executor-core",
   "crossbeam-channel",
   "timer",
+  "sync",
+  "net-driver",
 ]
 rt-full = [
+  "executor-core",
   "macros",
   "num_cpus",
   "net-full",
@@ -61,11 +66,13 @@ signal = [
   "libc",
   "mio-uds",
   "net-driver",
-  "signal-hook-registry"
+  "signal-hook-registry",
+  "winapi/consoleapi",
+  "winapi/minwindef",
 ]
 sync = ["fnv"]
 tcp = ["io", "net-driver"]
-timer = ["slab"]
+timer = ["executor-core", "sync", "slab"]
 udp = ["io", "net-driver"]
 uds = ["io", "net-driver", "mio-uds", "libc"]
 process = [
diff --git a/tokio/src/executor/current_thread/mod.rs b/tokio/src/executor/current_thread/mod.rs
index dcc9c51aca9..62619f2aa9f 100644
--- a/tokio/src/executor/current_thread/mod.rs
+++ b/tokio/src/executor/current_thread/mod.rs
@@ -18,10 +18,10 @@
 mod scheduler;
 use self::scheduler::{Scheduler, TickArgs};
 
-use crate::executor::{EnterError, Executor, SpawnError, TypedExecutor};
 #[cfg(feature = "blocking")]
 use crate::executor::blocking::{Pool, PoolWaiter};
 use crate::executor::park::{Park, ParkThread, Unpark};
+use crate::executor::{EnterError, Executor, SpawnError, TypedExecutor};
 
 use std::cell::Cell;
 use std::error::Error;
diff --git a/tokio/src/executor/thread_pool/pool.rs b/tokio/src/executor/thread_pool/pool.rs
index 1da4239be8f..6a83e97ddcf 100644
--- a/tokio/src/executor/thread_pool/pool.rs
+++ b/tokio/src/executor/thread_pool/pool.rs
@@ -68,8 +68,11 @@ impl ThreadPool {
         F: Future,
     {
         crate::executor::global::with_threadpool(self, || {
-            let mut enter = crate::executor::enter().expect("attempting to block while on a Tokio executor");
-            crate::executor::blocking::with_pool(self.spawner.blocking_pool(), || enter.block_on(future))
+            let mut enter =
+                crate::executor::enter().expect("attempting to block while on a Tokio executor");
+            crate::executor::blocking::with_pool(self.spawner.blocking_pool(), || {
+                enter.block_on(future)
+            })
         })
     }
 
diff --git a/tokio/src/lib.rs b/tokio/src/lib.rs
index 94eb3072eb7..f42a8a1e98c 100644
--- a/tokio/src/lib.rs
+++ b/tokio/src/lib.rs
@@ -95,7 +95,7 @@ pub mod fs;
 
 pub mod future;
 
-#[cfg(feature = "io")]
+#[cfg(feature = "io-traits")]
 pub mod io;
 
 #[cfg(feature = "net-driver")]
@@ -121,8 +121,10 @@ pub mod sync;
 #[cfg(feature = "timer")]
 pub mod timer;
 
+#[cfg(feature = "executor-core")]
+pub mod executor;
+
 if_runtime! {
-    pub mod executor;
     pub mod runtime;
 
     #[doc(inline)]