diff --git a/Cargo.lock b/Cargo.lock
index fa749e5e3aebe..5b446c517c915 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3325,8 +3325,6 @@ dependencies = [
  "log",
  "rustc",
  "rustc_data_structures",
- "rustc_errors",
- "syntax",
  "syntax_pos",
 ]
 
@@ -3348,7 +3346,6 @@ dependencies = [
  "log",
  "memmap",
  "num_cpus",
- "parking_lot 0.9.0",
  "rustc",
  "rustc_apfloat",
  "rustc_codegen_utils",
@@ -3367,7 +3364,6 @@ dependencies = [
 name = "rustc_codegen_utils"
 version = "0.0.0"
 dependencies = [
- "flate2",
  "log",
  "punycode",
  "rustc",
@@ -3562,7 +3558,6 @@ name = "rustc_mir"
 version = "0.0.0"
 dependencies = [
  "arena",
- "byteorder",
  "either",
  "graphviz",
  "log",
@@ -3615,7 +3610,6 @@ name = "rustc_plugin_impl"
 version = "0.0.0"
 dependencies = [
  "rustc",
- "rustc_errors",
  "rustc_metadata",
  "syntax",
  "syntax_pos",
@@ -3639,7 +3633,6 @@ version = "0.0.0"
 dependencies = [
  "arena",
  "bitflags",
- "indexmap",
  "log",
  "rustc",
  "rustc_data_structures",
@@ -3661,7 +3654,6 @@ dependencies = [
  "rustc_codegen_utils",
  "rustc_data_structures",
  "rustc_target",
- "rustc_typeck",
  "serde_json",
  "syntax",
  "syntax_pos",
@@ -3692,9 +3684,7 @@ checksum = "b725dadae9fabc488df69a287f5a99c5eaf5d10853842a8a3dfac52476f544ee"
 name = "rustc_traits"
 version = "0.0.0"
 dependencies = [
- "bitflags",
  "chalk-engine",
- "graphviz",
  "log",
  "rustc",
  "rustc_data_structures",
@@ -4057,7 +4047,6 @@ version = "0.0.0"
 dependencies = [
  "alloc",
  "backtrace",
- "cc",
  "cfg-if",
  "compiler_builtins",
  "core",
@@ -4242,7 +4231,6 @@ dependencies = [
  "rustc_data_structures",
  "rustc_errors",
  "rustc_lexer",
- "rustc_macros",
  "rustc_target",
  "scoped-tls",
  "serialize",
@@ -4258,7 +4246,6 @@ dependencies = [
  "log",
  "rustc_data_structures",
  "rustc_errors",
- "rustc_lexer",
  "rustc_target",
  "smallvec",
  "syntax",
diff --git a/src/librustc_ast_borrowck/Cargo.toml b/src/librustc_ast_borrowck/Cargo.toml
index 024b2640e1e8e..40c4c1fc3fee6 100644
--- a/src/librustc_ast_borrowck/Cargo.toml
+++ b/src/librustc_ast_borrowck/Cargo.toml
@@ -12,11 +12,9 @@ doctest = false
 
 [dependencies]
 log = "0.4"
-syntax = { path = "../libsyntax" }
 syntax_pos = { path = "../libsyntax_pos" }
 # for "clarity", rename the graphviz crate to dot; graphviz within `borrowck`
 # refers to the borrowck-specific graphviz adapter traits.
 dot = { path = "../libgraphviz", package = "graphviz" }
 rustc = { path = "../librustc" }
-errors = { path = "../librustc_errors", package = "rustc_errors" }
 rustc_data_structures = { path = "../librustc_data_structures" }
diff --git a/src/librustc_codegen_ssa/Cargo.toml b/src/librustc_codegen_ssa/Cargo.toml
index bc028d6624279..2e3666e609657 100644
--- a/src/librustc_codegen_ssa/Cargo.toml
+++ b/src/librustc_codegen_ssa/Cargo.toml
@@ -17,7 +17,6 @@ memmap = "0.6"
 log = "0.4.5"
 libc = "0.2.44"
 jobserver = "0.1.11"
-parking_lot = "0.9"
 tempfile = "3.1"
 
 rustc_serialize = { path = "../libserialize", package = "serialize" }
diff --git a/src/librustc_codegen_utils/Cargo.toml b/src/librustc_codegen_utils/Cargo.toml
index 89b50c5daccae..c8c219d039a73 100644
--- a/src/librustc_codegen_utils/Cargo.toml
+++ b/src/librustc_codegen_utils/Cargo.toml
@@ -10,7 +10,6 @@ path = "lib.rs"
 test = false
 
 [dependencies]
-flate2 = "1.0"
 log = "0.4"
 punycode = "0.4.0"
 rustc-demangle = "0.1.16"
diff --git a/src/librustc_mir/Cargo.toml b/src/librustc_mir/Cargo.toml
index 0691390bead4b..f296753a0304c 100644
--- a/src/librustc_mir/Cargo.toml
+++ b/src/librustc_mir/Cargo.toml
@@ -24,6 +24,5 @@ rustc_lexer = { path = "../librustc_lexer" }
 rustc_serialize = { path = "../libserialize", package = "serialize" }
 syntax = { path = "../libsyntax" }
 syntax_pos = { path = "../libsyntax_pos" }
-byteorder = { version = "1.3" }
 rustc_apfloat = { path = "../librustc_apfloat" }
 smallvec = { version = "0.6.7", features = ["union", "may_dangle"] }
diff --git a/src/librustc_plugin/Cargo.toml b/src/librustc_plugin/Cargo.toml
index 84a743ed1ad7d..3f11430dc82cb 100644
--- a/src/librustc_plugin/Cargo.toml
+++ b/src/librustc_plugin/Cargo.toml
@@ -15,4 +15,3 @@ rustc = { path = "../librustc" }
 rustc_metadata = { path = "../librustc_metadata" }
 syntax = { path = "../libsyntax" }
 syntax_pos = { path = "../libsyntax_pos" }
-rustc_errors = { path = "../librustc_errors" }
diff --git a/src/librustc_resolve/Cargo.toml b/src/librustc_resolve/Cargo.toml
index 548f982fe3bf0..936e72ef2c571 100644
--- a/src/librustc_resolve/Cargo.toml
+++ b/src/librustc_resolve/Cargo.toml
@@ -12,7 +12,6 @@ doctest = false
 
 [dependencies]
 bitflags = "1.0"
-indexmap = "1"
 log = "0.4"
 syntax = { path = "../libsyntax" }
 rustc = { path = "../librustc" }
diff --git a/src/librustc_save_analysis/Cargo.toml b/src/librustc_save_analysis/Cargo.toml
index 88bb76d2aba3a..b89c83d630b7d 100644
--- a/src/librustc_save_analysis/Cargo.toml
+++ b/src/librustc_save_analysis/Cargo.toml
@@ -14,7 +14,6 @@ rustc = { path = "../librustc" }
 rustc_data_structures = { path = "../librustc_data_structures" }
 rustc_codegen_utils = { path = "../librustc_codegen_utils" }
 rustc_target = { path = "../librustc_target" }
-rustc_typeck = { path = "../librustc_typeck" }
 serde_json = "1"
 syntax = { path = "../libsyntax" }
 syntax_pos = { path = "../libsyntax_pos" }
diff --git a/src/librustc_traits/Cargo.toml b/src/librustc_traits/Cargo.toml
index bb28ac839a544..b86a3a5e9639b 100644
--- a/src/librustc_traits/Cargo.toml
+++ b/src/librustc_traits/Cargo.toml
@@ -9,8 +9,6 @@ name = "rustc_traits"
 path = "lib.rs"
 
 [dependencies]
-bitflags = "1.0"
-graphviz = { path = "../libgraphviz" }
 log = { version = "0.4" }
 rustc = { path = "../librustc" }
 rustc_data_structures = { path = "../librustc_data_structures" }
diff --git a/src/libstd/Cargo.toml b/src/libstd/Cargo.toml
index af1d2402f88e7..ee4b367b5c5b9 100644
--- a/src/libstd/Cargo.toml
+++ b/src/libstd/Cargo.toml
@@ -53,9 +53,6 @@ fortanix-sgx-abi = { version = "0.3.2", features = ['rustc-dep-of-std'] }
 [target.wasm32-wasi.dependencies]
 wasi = { version = "0.7.0", features = ['rustc-dep-of-std', 'alloc'] }
 
-[build-dependencies]
-cc = "1.0"
-
 [features]
 default = ["std_detect_file_io", "std_detect_dlsym_getauxval"]
 
diff --git a/src/libsyntax/Cargo.toml b/src/libsyntax/Cargo.toml
index d4a9acc1569b4..196cf4d9dfae8 100644
--- a/src/libsyntax/Cargo.toml
+++ b/src/libsyntax/Cargo.toml
@@ -19,6 +19,5 @@ syntax_pos = { path = "../libsyntax_pos" }
 errors = { path = "../librustc_errors", package = "rustc_errors" }
 rustc_data_structures = { path = "../librustc_data_structures" }
 rustc_lexer = { path = "../librustc_lexer" }
-rustc_macros = { path = "../librustc_macros" }
 rustc_target = { path = "../librustc_target" }
 smallvec = { version = "0.6.7", features = ["union", "may_dangle"] }
diff --git a/src/libsyntax_ext/Cargo.toml b/src/libsyntax_ext/Cargo.toml
index 791ee94b4fa77..73310df305b32 100644
--- a/src/libsyntax_ext/Cargo.toml
+++ b/src/libsyntax_ext/Cargo.toml
@@ -18,4 +18,3 @@ rustc_target = { path = "../librustc_target" }
 smallvec = { version = "0.6.7", features = ["union", "may_dangle"] }
 syntax = { path = "../libsyntax" }
 syntax_pos = { path = "../libsyntax_pos" }
-rustc_lexer = { path = "../librustc_lexer" }