diff --git a/Cargo.lock b/Cargo.lock
index 8cbf6cf6869..e9fb097df92 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -65,9 +65,9 @@ dependencies = [
 
 [[package]]
 name = "anyhow"
-version = "1.0.26"
+version = "1.0.31"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7825f6833612eb2414095684fcf6c635becf3ce97fe48cf6421321e93bfbd53c"
+checksum = "85bb70cc08ec97ca5450e6eba421deeea5f172c0fc61f78b5357b2a8e8be195f"
 
 [[package]]
 name = "arc-swap"
@@ -143,15 +143,6 @@ dependencies = [
  "rustc-std-workspace-core",
 ]
 
-[[package]]
-name = "base64"
-version = "0.10.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0b25d992356d2eb0ed82172f5248873db5560c4721f564b13cb5193bda5e668e"
-dependencies = [
- "byteorder",
-]
-
 [[package]]
 name = "bitflags"
 version = "1.2.1"
@@ -270,7 +261,6 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "40ade3d27603c2cb345eb0912aec461a6dec7e06a4ae48589904e808335c7afa"
 dependencies = [
  "byteorder",
- "either",
  "iovec",
 ]
 
@@ -291,7 +281,7 @@ dependencies = [
  "cargo-test-macro",
  "cargo-test-support",
  "clap",
- "core-foundation 0.7.0",
+ "core-foundation",
  "crates-io",
  "crossbeam-utils 0.7.2",
  "crypto-hash",
@@ -539,7 +529,7 @@ dependencies = [
  "if_chain",
  "itertools 0.9.0",
  "lazy_static",
- "pulldown-cmark 0.7.1",
+ "pulldown-cmark",
  "quine-mc_cluskey",
  "quote 1.0.2",
  "regex-syntax",
@@ -570,26 +560,6 @@ dependencies = [
  "cc",
 ]
 
-[[package]]
-name = "codespan"
-version = "0.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "de67bdcd653002a6dba3eb53850ce3a485547225d81cb6c2bbdbc5a0cba5d15d"
-dependencies = [
- "unicode-segmentation",
-]
-
-[[package]]
-name = "codespan-reporting"
-version = "0.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "efd1d915d9e2b2ad696b2cd73215a84823ef3f0e3084d90304204415921b62c6"
-dependencies = [
- "codespan",
- "termcolor",
- "unicode-width",
-]
-
 [[package]]
 name = "colored"
 version = "1.9.3"
@@ -676,34 +646,6 @@ version = "0.1.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8ff012e225ce166d4422e0e78419d901719760f62ae2b7969ca6b564d1b54a9e"
 
-[[package]]
-name = "cookie"
-version = "0.12.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "888604f00b3db336d2af898ec3c1d5d0ddf5e6d462220f2ededc33a87ac4bbd5"
-dependencies = [
- "time",
- "url 1.7.2",
-]
-
-[[package]]
-name = "cookie_store"
-version = "0.7.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "46750b3f362965f197996c4448e4a0935e791bf7d6631bfce9ee0af3d24c919c"
-dependencies = [
- "cookie",
- "failure",
- "idna 0.1.5",
- "log",
- "publicsuffix",
- "serde",
- "serde_json",
- "time",
- "try_from",
- "url 1.7.2",
-]
-
 [[package]]
 name = "core"
 version = "0.0.0"
@@ -711,32 +653,16 @@ dependencies = [
  "rand 0.7.3",
 ]
 
-[[package]]
-name = "core-foundation"
-version = "0.6.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4e2640d6d0bf22e82bed1b73c6aef8d5dd31e5abe6666c57e6d45e2649f4f887"
-dependencies = [
- "core-foundation-sys 0.6.2",
- "libc",
-]
-
 [[package]]
 name = "core-foundation"
 version = "0.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "57d24c7a13c43e870e37c1556b74555437870a04514f7685f5b354e090567171"
 dependencies = [
- "core-foundation-sys 0.7.0",
+ "core-foundation-sys",
  "libc",
 ]
 
-[[package]]
-name = "core-foundation-sys"
-version = "0.6.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e7ca8a5221364ef15ce201e8ed2f609fc312682a8f4e0e3d4aa5879764e0fa3b"
-
 [[package]]
 name = "core-foundation-sys"
 version = "0.7.0"
@@ -881,40 +807,6 @@ dependencies = [
  "winapi 0.3.8",
 ]
 
-[[package]]
-name = "darling"
-version = "0.8.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9158d690bc62a3a57c3e45b85e4d50de2008b39345592c64efd79345c7e24be0"
-dependencies = [
- "darling_core",
- "darling_macro",
-]
-
-[[package]]
-name = "darling_core"
-version = "0.8.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d2a368589465391e127e10c9e3a08efc8df66fd49b87dc8524c764bbe7f2ef82"
-dependencies = [
- "fnv",
- "ident_case",
- "proc-macro2 0.4.30",
- "quote 0.6.12",
- "syn 0.15.35",
-]
-
-[[package]]
-name = "darling_macro"
-version = "0.8.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "244e8987bd4e174385240cde20a3657f607fb0797563c28255c353b5819a07b1"
-dependencies = [
- "darling_core",
- "quote 0.6.12",
- "syn 0.15.35",
-]
-
 [[package]]
 name = "datafrog"
 version = "2.0.1"
@@ -1007,18 +899,6 @@ dependencies = [
  "rustc-std-workspace-core",
 ]
 
-[[package]]
-name = "dtoa"
-version = "0.4.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ea57b42383d091c85abcc2706240b94ab2a8fa1fc81c10ff23c4de06e2a90b5e"
-
-[[package]]
-name = "dunce"
-version = "1.0.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d0ad6bf6a88548d1126045c413548df1453d9be094a8ab9fd59bf1fdd338da4f"
-
 [[package]]
 name = "either"
 version = "1.5.0"
@@ -1049,15 +929,6 @@ dependencies = [
  "log",
 ]
 
-[[package]]
-name = "encoding_rs"
-version = "0.8.17"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4155785c79f2f6701f185eb2e6b4caf0555ec03477cb4c70db67b465311620ed"
-dependencies = [
- "cfg-if",
-]
-
 [[package]]
 name = "env_logger"
 version = "0.6.2"
@@ -1084,15 +955,6 @@ dependencies = [
  "termcolor",
 ]
 
-[[package]]
-name = "error-chain"
-version = "0.12.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "07e791d3be96241c77c43846b665ef1384606da2cd2a48730abe606a12906e02"
-dependencies = [
- "backtrace",
-]
-
 [[package]]
 name = "error_index_generator"
 version = "0.0.0"
@@ -1252,16 +1114,6 @@ version = "0.1.28"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "45dc39533a6cae6da2b56da48edae506bb767ec07370f86f70fc062e9d435869"
 
-[[package]]
-name = "futures-cpupool"
-version = "0.1.8"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ab90cde24b3319636588d0c35fe03b1333857621051837ed769faefb4c2162e4"
-dependencies = [
- "futures",
- "num_cpus",
-]
-
 [[package]]
 name = "fwdansi"
 version = "1.0.1"
@@ -1349,24 +1201,6 @@ dependencies = [
  "regex",
 ]
 
-[[package]]
-name = "h2"
-version = "0.1.25"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a539b63339fbbb00e081e84b6e11bd1d9634a82d91da2984a18ac74a8823f392"
-dependencies = [
- "byteorder",
- "bytes",
- "fnv",
- "futures",
- "http",
- "indexmap",
- "log",
- "slab",
- "string",
- "tokio-io",
-]
-
 [[package]]
 name = "handlebars"
 version = "3.0.1"
@@ -1449,35 +1283,6 @@ dependencies = [
  "syn 1.0.11",
 ]
 
-[[package]]
-name = "http"
-version = "0.1.19"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d7e06e336150b178206af098a055e3621e8336027e2b4d126bda0bc64824baaf"
-dependencies = [
- "bytes",
- "fnv",
- "itoa",
-]
-
-[[package]]
-name = "http-body"
-version = "0.1.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6741c859c1b2463a423a1dbce98d418e6c3c3fc720fb0d45528657320920292d"
-dependencies = [
- "bytes",
- "futures",
- "http",
- "tokio-buf",
-]
-
-[[package]]
-name = "httparse"
-version = "1.3.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cd179ae861f0c2e53da70d892f5f3029f9594be0c41dc5269cd371691b1dc2f9"
-
 [[package]]
 name = "humantime"
 version = "1.3.0"
@@ -1493,55 +1298,6 @@ version = "2.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b9b6c53306532d3c8e8087b44e6580e10db51a023cf9b433cea2ac38066b92da"
 
-[[package]]
-name = "hyper"
-version = "0.12.31"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6481fff8269772d4463253ca83c788104a7305cb3fb9136bc651a6211e46e03f"
-dependencies = [
- "bytes",
- "futures",
- "futures-cpupool",
- "h2",
- "http",
- "http-body",
- "httparse",
- "iovec",
- "itoa",
- "log",
- "net2",
- "rustc_version",
- "time",
- "tokio",
- "tokio-buf",
- "tokio-executor",
- "tokio-io",
- "tokio-reactor",
- "tokio-tcp",
- "tokio-threadpool",
- "tokio-timer",
- "want",
-]
-
-[[package]]
-name = "hyper-tls"
-version = "0.3.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3a800d6aa50af4b5850b2b0f659625ce9504df908e9733b635720483be26174f"
-dependencies = [
- "bytes",
- "futures",
- "hyper",
- "native-tls",
- "tokio-io",
-]
-
-[[package]]
-name = "ident_case"
-version = "1.0.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b9e0384b61958566e926dc50660321d12159025e767c18e043daf26b70104c39"
-
 [[package]]
 name = "idna"
 version = "0.1.5"
@@ -1634,12 +1390,6 @@ dependencies = [
  "libc",
 ]
 
-[[package]]
-name = "is-match"
-version = "0.1.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7e5b386aef33a1c677be65237cb9d32c3f3ef56bd035949710c4bb13083eb053"
-
 [[package]]
 name = "itertools"
 version = "0.8.0"
@@ -1992,23 +1742,22 @@ dependencies = [
 
 [[package]]
 name = "mdbook"
-version = "0.3.7"
+version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e7ec525f7ebccc2dd935c263717250cd37f9a4b264a77c5dbc950ea2734d8159"
+checksum = "2567ffadc0fd26fe15d6f6e0a80639f19f6a50082fdb460d0ae5d1f7298181be"
 dependencies = [
  "ammonia",
+ "anyhow",
  "chrono",
  "clap",
  "elasticlunr-rs",
- "env_logger 0.6.2",
- "error-chain",
+ "env_logger 0.7.1",
  "handlebars",
- "itertools 0.8.0",
  "lazy_static",
  "log",
  "memchr",
  "open",
- "pulldown-cmark 0.6.1",
+ "pulldown-cmark",
  "regex",
  "serde",
  "serde_derive",
@@ -2016,34 +1765,6 @@ dependencies = [
  "shlex",
  "tempfile",
  "toml",
- "toml-query",
-]
-
-[[package]]
-name = "mdbook-linkcheck"
-version = "0.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c0a04db564ca37c47771f8455c825dc941ea851ff0deffcf55a04c512406b409"
-dependencies = [
- "codespan",
- "codespan-reporting",
- "dunce",
- "either",
- "env_logger 0.7.1",
- "failure",
- "http",
- "log",
- "mdbook",
- "percent-encoding 2.1.0",
- "pulldown-cmark 0.6.1",
- "rayon",
- "regex",
- "reqwest",
- "semver 0.9.0",
- "serde",
- "serde_derive",
- "serde_json",
- "structopt",
 ]
 
 [[package]]
@@ -2083,25 +1804,6 @@ dependencies = [
  "rustc_version",
 ]
 
-[[package]]
-name = "mime"
-version = "0.3.13"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3e27ca21f40a310bd06d9031785f4801710d566c184a6e15bad4f1d9b65f9425"
-dependencies = [
- "unicase",
-]
-
-[[package]]
-name = "mime_guess"
-version = "2.0.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1a0ed03949aef72dbdf3116a383d7b38b4768e6f960528cd6a6044aa9ed68599"
-dependencies = [
- "mime",
- "unicase",
-]
-
 [[package]]
 name = "minifier"
 version = "0.0.33"
@@ -2202,24 +1904,6 @@ dependencies = [
  "shell-escape",
 ]
 
-[[package]]
-name = "native-tls"
-version = "0.2.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4b2df1a4c22fd44a62147fd8f13dd0f95c9d8ca7b2610299b2a2f9cf8964274e"
-dependencies = [
- "lazy_static",
- "libc",
- "log",
- "openssl",
- "openssl-probe",
- "openssl-sys",
- "schannel",
- "security-framework",
- "security-framework-sys",
- "tempfile",
-]
-
 [[package]]
 name = "net2"
 version = "0.2.33"
@@ -2670,31 +2354,6 @@ dependencies = [
  "cc",
 ]
 
-[[package]]
-name = "publicsuffix"
-version = "1.5.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9bf259a81de2b2eb9850ec990ec78e6a25319715584fd7652b9b26f96fcb1510"
-dependencies = [
- "error-chain",
- "idna 0.2.0",
- "lazy_static",
- "regex",
- "url 2.1.0",
-]
-
-[[package]]
-name = "pulldown-cmark"
-version = "0.6.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1c205cc82214f3594e2d50686730314f817c67ffa80fe800cf0db78c3c2b9d9e"
-dependencies = [
- "bitflags",
- "getopts",
- "memchr",
- "unicase",
-]
-
 [[package]]
 name = "pulldown-cmark"
 version = "0.7.1"
@@ -2702,6 +2361,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3e142c3b8f49d2200605ee6ba0b1d757310e9e7a72afe78c36ee2ef67300ee00"
 dependencies = [
  "bitflags",
+ "getopts",
  "memchr",
  "unicase",
 ]
@@ -3002,40 +2662,6 @@ dependencies = [
  "winapi 0.3.8",
 ]
 
-[[package]]
-name = "reqwest"
-version = "0.9.22"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2c2064233e442ce85c77231ebd67d9eca395207dec2127fe0bbedde4bd29a650"
-dependencies = [
- "base64",
- "bytes",
- "cookie",
- "cookie_store",
- "encoding_rs",
- "flate2",
- "futures",
- "http",
- "hyper",
- "hyper-tls",
- "log",
- "mime",
- "mime_guess",
- "native-tls",
- "serde",
- "serde_json",
- "serde_urlencoded",
- "time",
- "tokio",
- "tokio-executor",
- "tokio-io",
- "tokio-threadpool",
- "tokio-timer",
- "url 1.7.2",
- "uuid",
- "winreg",
-]
-
 [[package]]
 name = "rls"
 version = "1.41.0"
@@ -3162,12 +2788,7 @@ name = "rustbook"
 version = "0.1.0"
 dependencies = [
  "clap",
- "codespan",
- "codespan-reporting",
- "failure",
  "mdbook",
- "mdbook-linkcheck",
- "rustc-workspace-hack",
 ]
 
 [[package]]
@@ -4402,7 +4023,7 @@ version = "0.0.0"
 dependencies = [
  "itertools 0.8.0",
  "minifier",
- "pulldown-cmark 0.7.1",
+ "pulldown-cmark",
  "rustc-rayon",
  "serde",
  "serde_json",
@@ -4525,27 +4146,6 @@ version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b42e15e59b18a828bbf5c58ea01debb36b9b096346de35d941dcb89009f24a0d"
 
-[[package]]
-name = "security-framework"
-version = "0.3.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "eee63d0f4a9ec776eeb30e220f0bc1e092c3ad744b2a379e3993070364d3adc2"
-dependencies = [
- "core-foundation 0.6.3",
- "core-foundation-sys 0.6.2",
- "libc",
- "security-framework-sys",
-]
-
-[[package]]
-name = "security-framework-sys"
-version = "0.3.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9636f8989cbf61385ae4824b98c1aaa54c994d7d8b41f11c601ed799f0549a56"
-dependencies = [
- "core-foundation-sys 0.6.2",
-]
-
 [[package]]
 name = "semver"
 version = "0.9.0"
@@ -4623,18 +4223,6 @@ dependencies = [
  "syn 1.0.11",
 ]
 
-[[package]]
-name = "serde_urlencoded"
-version = "0.5.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "642dd69105886af2efd227f75a520ec9b44a820d65bc133a9131f7d229fd165a"
-dependencies = [
- "dtoa",
- "itoa",
- "serde",
- "url 1.7.2",
-]
-
 [[package]]
 name = "sha-1"
 version = "0.8.2"
@@ -4756,15 +4344,6 @@ dependencies = [
  "wasi",
 ]
 
-[[package]]
-name = "string"
-version = "0.2.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d24114bfcceb867ca7f71a0d3fe45d45619ec47a6fbfa98cb14e14250bfa5d6d"
-dependencies = [
- "bytes",
-]
-
 [[package]]
 name = "string_cache"
 version = "0.7.3"
@@ -5072,17 +4651,6 @@ dependencies = [
  "tokio-uds",
 ]
 
-[[package]]
-name = "tokio-buf"
-version = "0.1.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8fb220f46c53859a4b7ec083e41dec9778ff0b1851c0942b211edb89e0ccdc46"
-dependencies = [
- "bytes",
- "either",
- "futures",
-]
-
 [[package]]
 name = "tokio-codec"
 version = "0.1.1"
@@ -5308,32 +4876,6 @@ dependencies = [
  "serde",
 ]
 
-[[package]]
-name = "toml-query"
-version = "0.9.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a24369a1894ac8224efcfd567c3d141aea360292f49888e7ec7dcc316527aebb"
-dependencies = [
- "failure",
- "failure_derive",
- "is-match",
- "lazy_static",
- "regex",
- "toml",
- "toml-query_derive",
-]
-
-[[package]]
-name = "toml-query_derive"
-version = "0.9.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3c99ca245ec273c7e75c8ee58f47b882d0146f3c2c8495158082c6671e8b5335"
-dependencies = [
- "darling",
- "quote 0.6.12",
- "syn 0.15.35",
-]
-
 [[package]]
 name = "tracing"
 version = "0.1.15"
@@ -5365,21 +4907,6 @@ dependencies = [
  "lazy_static",
 ]
 
-[[package]]
-name = "try-lock"
-version = "0.2.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e604eb7b43c06650e854be16a2a03155743d3752dd1c943f6829e26b7a36e382"
-
-[[package]]
-name = "try_from"
-version = "0.3.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "283d3b89e1368717881a9d51dad843cc435380d8109c9e47d38780a324698d8b"
-dependencies = [
- "cfg-if",
-]
-
 [[package]]
 name = "typenum"
 version = "1.12.0"
@@ -5541,15 +5068,6 @@ version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8772a4ccbb4e89959023bc5b7cb8623a795caa7092d99f3aa9501b9484d4557d"
 
-[[package]]
-name = "uuid"
-version = "0.7.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "90dbc611eb48397705a6b0f6e917da23ae517e4d127123d2cf7674206627d32a"
-dependencies = [
- "rand 0.6.1",
-]
-
 [[package]]
 name = "vcpkg"
 version = "0.2.8"
@@ -5598,17 +5116,6 @@ dependencies = [
  "winapi-util",
 ]
 
-[[package]]
-name = "want"
-version = "0.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b6395efa4784b027708f7451087e647ec73cc74f5d9bc2e418404248d679a230"
-dependencies = [
- "futures",
- "log",
- "try-lock",
-]
-
 [[package]]
 name = "wasi"
 version = "0.9.0+wasi-snapshot-preview1"
@@ -5673,15 +5180,6 @@ dependencies = [
  "winapi-util",
 ]
 
-[[package]]
-name = "winreg"
-version = "0.6.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b2986deb581c4fe11b621998a5e53361efe6b48a151178d0cd9eeffa4dc6acc9"
-dependencies = [
- "winapi 0.3.8",
-]
-
 [[package]]
 name = "ws2_32-sys"
 version = "0.2.1"
diff --git a/src/bootstrap/tool.rs b/src/bootstrap/tool.rs
index 0055dee6092..063fb8fbb95 100644
--- a/src/bootstrap/tool.rs
+++ b/src/bootstrap/tool.rs
@@ -12,7 +12,7 @@
 use crate::channel::GitInfo;
 use crate::compile;
 use crate::toolstate::ToolState;
-use crate::util::{add_dylib_path, exe, CiEnv};
+use crate::util::{add_dylib_path, exe};
 use crate::Compiler;
 use crate::Mode;
 
@@ -236,7 +236,6 @@ pub fn prepare_tool_cargo(
             || path.ends_with("rls")
             || path.ends_with("clippy")
             || path.ends_with("miri")
-            || path.ends_with("rustbook")
             || path.ends_with("rustfmt")
         {
             cargo.env("LIBZ_SYS_STATIC", "1");
@@ -272,20 +271,6 @@ pub fn prepare_tool_cargo(
     cargo
 }
 
-fn rustbook_features() -> Vec<String> {
-    let mut features = Vec::new();
-
-    // Due to CI budged and risk of spurious failures we want to limit jobs running this check.
-    // At same time local builds should run it regardless of the platform.
-    // `CiEnv::None` means it's local build and `CHECK_LINKS` is defined in x86_64-gnu-tools to
-    // explicitly enable it on single job
-    if CiEnv::current() == CiEnv::None || env::var("CHECK_LINKS").is_ok() {
-        features.push("linkcheck".to_string());
-    }
-
-    features
-}
-
 macro_rules! bootstrap_tool {
     ($(
         $name:ident, $path:expr, $tool_name:expr
@@ -368,7 +353,7 @@ fn run(self, builder: &Builder<'_>) -> PathBuf {
 }
 
 bootstrap_tool!(
-    Rustbook, "src/tools/rustbook", "rustbook", features = rustbook_features();
+    Rustbook, "src/tools/rustbook", "rustbook";
     UnstableBookGen, "src/tools/unstable-book-gen", "unstable-book-gen";
     Tidy, "src/tools/tidy", "tidy";
     Linkchecker, "src/tools/linkchecker", "linkchecker";
diff --git a/src/ci/docker/x86_64-gnu-tools/Dockerfile b/src/ci/docker/x86_64-gnu-tools/Dockerfile
index 148e09f6ad1..3b6e4c2cb98 100644
--- a/src/ci/docker/x86_64-gnu-tools/Dockerfile
+++ b/src/ci/docker/x86_64-gnu-tools/Dockerfile
@@ -19,9 +19,6 @@ RUN sh /scripts/sccache.sh
 
 COPY x86_64-gnu-tools/checktools.sh /tmp/
 
-# Run rustbook with `linkcheck` feature enabled
-ENV CHECK_LINKS 1
-
 ENV RUST_CONFIGURE_ARGS \
   --build=x86_64-unknown-linux-gnu \
   --save-toolstates=/tmp/toolstate/toolstates.json
diff --git a/src/tools/rustbook/Cargo.toml b/src/tools/rustbook/Cargo.toml
index ff41197faa1..f0a6ce2fa06 100644
--- a/src/tools/rustbook/Cargo.toml
+++ b/src/tools/rustbook/Cargo.toml
@@ -5,24 +5,10 @@ version = "0.1.0"
 license = "MIT OR Apache-2.0"
 edition = "2018"
 
-[features]
-linkcheck = ["mdbook-linkcheck", "codespan-reporting", "codespan"]
-
 [dependencies]
 clap = "2.25.0"
-failure = "0.1"
-mdbook-linkcheck = { version = "0.5.0", optional = true }
-# Keep in sync with mdbook-linkcheck.
-codespan = { version = "0.5", optional = true }
-codespan-reporting = { version = "0.5", optional = true }
-
-
-# A noop dependency that changes in the Rust repository, it's a bit of a hack.
-# See the `src/tools/rustc-workspace-hack/README.md` file in `rust-lang/rust`
-# for more information.
-rustc-workspace-hack = "1.0.0"
 
 [dependencies.mdbook]
-version = "0.3.7"
+version = "0.4.0"
 default-features = false
 features = ["search"]
diff --git a/src/tools/rustbook/src/main.rs b/src/tools/rustbook/src/main.rs
index 60bd0b72910..c87c64540ad 100644
--- a/src/tools/rustbook/src/main.rs
+++ b/src/tools/rustbook/src/main.rs
@@ -30,11 +30,6 @@ fn main() {
                 .about("Tests that a book's Rust code samples compile")
                 .arg_from_usage(dir_message),
         )
-        .subcommand(
-            SubCommand::with_name("linkcheck")
-                .about("Run linkcheck with mdBook 3")
-                .arg_from_usage(dir_message),
-        )
         .get_matches();
 
     // Check which subcomamnd the user ran...
@@ -49,98 +44,14 @@ fn main() {
                 handle_error(e);
             }
         }
-        ("linkcheck", Some(sub_matches)) => {
-            #[cfg(feature = "linkcheck")]
-            {
-                let (diags, files) = linkcheck(sub_matches).expect("Error while linkchecking.");
-                if !diags.is_empty() {
-                    let color = codespan_reporting::term::termcolor::ColorChoice::Auto;
-                    let mut writer =
-                        codespan_reporting::term::termcolor::StandardStream::stderr(color);
-                    let cfg = codespan_reporting::term::Config::default();
-
-                    for diag in diags {
-                        codespan_reporting::term::emit(&mut writer, &cfg, &files, &diag)
-                            .expect("Unable to emit linkcheck error.");
-                    }
-
-                    std::process::exit(101);
-                }
-            }
-
-            #[cfg(not(feature = "linkcheck"))]
-            {
-                // This avoids the `unused_binding` lint.
-                println!(
-                    "mdbook-linkcheck is disabled, but arguments were passed: {:?}",
-                    sub_matches
-                );
-            }
-        }
         (_, _) => unreachable!(),
     };
 }
 
-#[cfg(feature = "linkcheck")]
-pub fn linkcheck(
-    args: &ArgMatches<'_>,
-) -> Result<(Vec<codespan_reporting::diagnostic::Diagnostic>, codespan::Files), failure::Error> {
-    use mdbook_linkcheck::Reason;
-
-    let book_dir = get_book_dir(args);
-    let src_dir = book_dir.join("src");
-    let book = MDBook::load(&book_dir).unwrap();
-    let linkck_cfg = mdbook_linkcheck::get_config(&book.config)?;
-    let mut files = codespan::Files::new();
-    let target_files = mdbook_linkcheck::load_files_into_memory(&book.book, &mut files);
-    let cache = mdbook_linkcheck::Cache::default();
-
-    let (links, incomplete) = mdbook_linkcheck::extract_links(target_files, &files);
-
-    let outcome =
-        mdbook_linkcheck::validate(&links, &linkck_cfg, &src_dir, &cache, &files, incomplete)?;
-
-    let mut is_real_error = false;
-
-    for link in outcome.invalid_links.iter() {
-        match &link.reason {
-            Reason::FileNotFound | Reason::TraversesParentDirectories => {
-                is_real_error = true;
-            }
-            Reason::UnsuccessfulServerResponse(status) => {
-                if status.as_u16() == 429 {
-                    eprintln!("Received 429 (TOO_MANY_REQUESTS) for link `{}`", link.link.uri);
-                } else if status.is_client_error() {
-                    is_real_error = true;
-                } else {
-                    eprintln!("Unsuccessful server response for link `{}`", link.link.uri);
-                }
-            }
-            Reason::Client(err) => {
-                if err.is_timeout() {
-                    eprintln!("Timeout for link `{}`", link.link.uri);
-                } else if err.is_server_error() {
-                    eprintln!("Server error for link `{}`", link.link.uri);
-                } else if !err.is_http() {
-                    eprintln!("Non-HTTP-related error for link: {} {}", link.link.uri, err);
-                } else {
-                    is_real_error = true;
-                }
-            }
-        }
-    }
-
-    if is_real_error {
-        Ok((outcome.generate_diagnostics(&files, linkck_cfg.warning_policy), files))
-    } else {
-        Ok((vec![], files))
-    }
-}
-
 // Build command implementation
 pub fn build(args: &ArgMatches<'_>) -> Result3<()> {
     let book_dir = get_book_dir(args);
-    let mut book = MDBook::load(&book_dir)?;
+    let mut book = load_book(&book_dir)?;
 
     // Set this to allow us to catch bugs in advance.
     book.config.build.create_missing = false;
@@ -156,7 +67,7 @@ pub fn build(args: &ArgMatches<'_>) -> Result3<()> {
 
 fn test(args: &ArgMatches<'_>) -> Result3<()> {
     let book_dir = get_book_dir(args);
-    let mut book = MDBook::load(&book_dir)?;
+    let mut book = load_book(&book_dir)?;
     book.test(vec![])
 }
 
@@ -170,10 +81,16 @@ fn get_book_dir(args: &ArgMatches<'_>) -> PathBuf {
     }
 }
 
+fn load_book(book_dir: &Path) -> Result3<MDBook> {
+    let mut book = MDBook::load(book_dir)?;
+    book.config.set("output.html.input-404", "").unwrap();
+    Ok(book)
+}
+
 fn handle_error(error: mdbook::errors::Error) -> ! {
     eprintln!("Error: {}", error);
 
-    for cause in error.iter().skip(1) {
+    for cause in error.chain().skip(1) {
         eprintln!("\tCaused By: {}", cause);
     }
 
diff --git a/src/tools/tidy/src/deps.rs b/src/tools/tidy/src/deps.rs
index 093db2a49d0..4622e15a1ca 100644
--- a/src/tools/tidy/src/deps.rs
+++ b/src/tools/tidy/src/deps.rs
@@ -26,9 +26,6 @@
 const EXCEPTIONS: &[(&str, &str)] = &[
     ("mdbook", "MPL-2.0"),                  // mdbook
     ("openssl", "Apache-2.0"),              // cargo, mdbook
-    ("toml-query", "MPL-2.0"),              // mdbook
-    ("toml-query_derive", "MPL-2.0"),       // mdbook
-    ("is-match", "MPL-2.0"),                // mdbook
     ("rdrand", "ISC"),                      // mdbook, rustfmt
     ("fuchsia-cprng", "BSD-3-Clause"),      // mdbook, rustfmt
     ("fuchsia-zircon-sys", "BSD-3-Clause"), // rustdoc, rustc, cargo
@@ -45,9 +42,6 @@
     ("bitmaps", "MPL-2.0+"),                // cargo via im-rc
     // FIXME: this dependency violates the documentation comment above:
     ("fortanix-sgx-abi", "MPL-2.0"), // libstd but only for `sgx` target
-    ("dunce", "CC0-1.0"),            // mdbook-linkcheck
-    ("codespan-reporting", "Apache-2.0"), // mdbook-linkcheck
-    ("codespan", "Apache-2.0"),      // mdbook-linkcheck
     ("crossbeam-channel", "MIT/Apache-2.0 AND BSD-2-Clause"), // cargo
 ];