diff --git a/src/liballoc/lib.rs b/src/liballoc/lib.rs
index 82bd13475c74eabb6f106112edd5434c7411cc70..828e6b8dd7614b93a8d191808bbd7073c5ec2b2d 100644
--- a/src/liballoc/lib.rs
+++ b/src/liballoc/lib.rs
@@ -56,6 +56,8 @@
 //! The [`heap`](heap/index.html) module defines the low-level interface to the
 //! default global allocator. It is not compatible with the libc allocator API.
 
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "alloc"]
 #![unstable(feature = "alloc")]
 #![feature(staged_api)]
diff --git a/src/libarena/lib.rs b/src/libarena/lib.rs
index b43f9adfb26d92ed9c8f8f4ee8df7bc634c0cb46..b2ac9a34b0269fc7f7daa3157eefd6f2d356659b 100644
--- a/src/libarena/lib.rs
+++ b/src/libarena/lib.rs
@@ -19,6 +19,8 @@
 //! arena but can only hold objects of a single type, and `Arena`, which is a
 //! more complex, slower arena which can hold objects of any type.
 
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "arena"]
 #![unstable(feature = "rustc_private")]
 #![staged_api]
diff --git a/src/libcollections/lib.rs b/src/libcollections/lib.rs
index 7b66bfee34f2121b15f4e06ae47e832ed4a7edcf..9c1c2cc5906ebca14ebd09ae361595ba4a9ad73d 100644
--- a/src/libcollections/lib.rs
+++ b/src/libcollections/lib.rs
@@ -12,7 +12,8 @@
 //!
 //! See [std::collections](../std/collections) for a detailed discussion of collections in Rust.
 
-
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "collections"]
 #![unstable(feature = "collections")]
 #![staged_api]
diff --git a/src/libcore/lib.rs b/src/libcore/lib.rs
index 7cc963bed358f9aa666ff401bc3f520a3d84109a..ea39ab3da5e7815b5232821ba101cee6d11381f4 100644
--- a/src/libcore/lib.rs
+++ b/src/libcore/lib.rs
@@ -47,6 +47,8 @@
 // Since libcore defines many fundamental lang items, all tests live in a
 // separate crate, libcoretest, to avoid bizarre issues.
 
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "core"]
 #![unstable(feature = "core")]
 #![staged_api]
diff --git a/src/libcoretest/lib.rs b/src/libcoretest/lib.rs
index 03924910e0485d12acf5f4c86798842dacac6fe6..1dbbb845d46e0f87fad11e82cc358fe255eb9a2e 100644
--- a/src/libcoretest/lib.rs
+++ b/src/libcoretest/lib.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![feature(box_syntax)]
 #![feature(int_uint)]
 #![feature(unboxed_closures)]
diff --git a/src/libflate/lib.rs b/src/libflate/lib.rs
index 2ce52cdec2560a92ee1e32559e2ae4392b73e37e..ec75c1022248e25912c49ff844d11bb0912457a5 100644
--- a/src/libflate/lib.rs
+++ b/src/libflate/lib.rs
@@ -14,6 +14,8 @@
 //! [def]: https://en.wikipedia.org/wiki/DEFLATE
 //! [mz]: https://code.google.com/p/miniz/
 
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "flate"]
 #![unstable(feature = "rustc_private")]
 #![staged_api]
diff --git a/src/libfmt_macros/lib.rs b/src/libfmt_macros/lib.rs
index 4e25e51e9a466075c58b49ae0207413b88a8b426..9b220409ef59789b162b2ce380ade3d05624e39b 100644
--- a/src/libfmt_macros/lib.rs
+++ b/src/libfmt_macros/lib.rs
@@ -14,6 +14,8 @@
 //! Parsing does not happen at runtime: structures of `std::fmt::rt` are
 //! generated instead.
 
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "fmt_macros"]
 #![unstable(feature = "rustc_private")]
 #![staged_api]
diff --git a/src/libgetopts/lib.rs b/src/libgetopts/lib.rs
index 6240b0e6afdd50861f59ced7b8a752cd8dd626b9..c33c48476d56c9498e4cabc3be958ab161687430 100644
--- a/src/libgetopts/lib.rs
+++ b/src/libgetopts/lib.rs
@@ -77,6 +77,9 @@
 //! }
 //! ```
 
+
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "getopts"]
 #![unstable(feature = "rustc_private",
             reason = "use the crates.io `getopts` library instead")]
diff --git a/src/libgraphviz/lib.rs b/src/libgraphviz/lib.rs
index 09fbf4935e4c1e7a86ade0c5bdb543854bb313a8..751cbe688d19283ec2f43b973ae269182a3a5241 100644
--- a/src/libgraphviz/lib.rs
+++ b/src/libgraphviz/lib.rs
@@ -264,6 +264,8 @@
 //!
 //! * [DOT language](http://www.graphviz.org/doc/info/lang.html)
 
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "graphviz"]
 #![unstable(feature = "rustc_private")]
 #![feature(staged_api)]
diff --git a/src/liblibc/lib.rs b/src/liblibc/lib.rs
index 42143b06ca0e391678583b6e9cfced390ffa897c..4051ae9d33aac3e0a1ef2f57f308dd0ca0b41c42 100644
--- a/src/liblibc/lib.rs
+++ b/src/liblibc/lib.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "libc"]
 #![crate_type = "rlib"]
 #![cfg_attr(not(feature = "cargo-build"),
diff --git a/src/liblog/lib.rs b/src/liblog/lib.rs
index d0105bb65776eb6d216ba43580b2f768bbd41976..3b6e1d0469148eaf404aed34b26e1c7b8dc793c7 100644
--- a/src/liblog/lib.rs
+++ b/src/liblog/lib.rs
@@ -155,6 +155,8 @@
 //! they're turned off (just a load and an integer comparison). This also means that
 //! if logging is disabled, none of the components of the log will be executed.
 
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "log"]
 #![unstable(feature = "rustc_private",
             reason = "use the crates.io `log` library instead")]
diff --git a/src/librand/lib.rs b/src/librand/lib.rs
index 583c658dfe0582f3b02847e71aab3d4770620237..7acd6cda0445797480120feae01556e9b9575e2a 100644
--- a/src/librand/lib.rs
+++ b/src/librand/lib.rs
@@ -16,6 +16,8 @@
 //! is not recommended to use this library directly, but rather the official
 //! interface through `std::rand`.
 
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "rand"]
 #![crate_type = "rlib"]
 #![doc(html_logo_url = "http://www.rust-lang.org/logos/rust-logo-128x128-blk.png",
diff --git a/src/librbml/lib.rs b/src/librbml/lib.rs
index 05cd24de7368c6a831597d8e9aa4e096c916adf8..c247e3a3decc494440e54cbbfee7ace802e4ad33 100644
--- a/src/librbml/lib.rs
+++ b/src/librbml/lib.rs
@@ -15,6 +15,8 @@
 //! It is loosely based on the Extensible Binary Markup Language (ebml):
 //!     http://www.matroska.org/technical/specs/rfc/index.html
 
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "rbml"]
 #![unstable(feature = "rustc_private")]
 #![staged_api]
diff --git a/src/librustc/lib.rs b/src/librustc/lib.rs
index aa51320ee7f43ee0c861beeedfb56c76f1b0f911..53f44c0eb1ba647f550d223da91ee5635ba0c8b0 100644
--- a/src/librustc/lib.rs
+++ b/src/librustc/lib.rs
@@ -14,6 +14,8 @@
 //!
 //! This API is completely unstable and subject to change.
 
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "rustc"]
 #![unstable(feature = "rustc_private")]
 #![staged_api]
@@ -40,7 +42,6 @@
 #![feature(std_misc)]
 #![feature(os)]
 #![cfg_attr(test, feature(test))]
-
 extern crate arena;
 extern crate flate;
 extern crate fmt_macros;
diff --git a/src/librustc_back/lib.rs b/src/librustc_back/lib.rs
index 9005c666afbcdd254b1c3503b3796663e667a7e4..f5fab17006c157d88e3b8aa75b2834ee090c1fd1 100644
--- a/src/librustc_back/lib.rs
+++ b/src/librustc_back/lib.rs
@@ -21,6 +21,8 @@
 //! one that doesn't; the one that doesn't might get decent parallel
 //! build speedups.
 
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "rustc_back"]
 #![unstable(feature = "rustc_private")]
 #![staged_api]
diff --git a/src/librustc_bitflags/lib.rs b/src/librustc_bitflags/lib.rs
index 370a5d48decaec85298da73575468e6a98efb5f0..5115e9a4a20728b332565746dc2459ab96c87efa 100644
--- a/src/librustc_bitflags/lib.rs
+++ b/src/librustc_bitflags/lib.rs
@@ -8,6 +8,9 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "rustc_bitflags"]
 #![feature(staged_api)]
 #![staged_api]
diff --git a/src/librustc_borrowck/lib.rs b/src/librustc_borrowck/lib.rs
index b7cfda280925701495074fcb68d1955b03b3a058..e09457970e12f776513d60245527aab02288f6c5 100644
--- a/src/librustc_borrowck/lib.rs
+++ b/src/librustc_borrowck/lib.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "rustc_borrowck"]
 #![unstable(feature = "rustc_private")]
 #![staged_api]
diff --git a/src/librustc_driver/lib.rs b/src/librustc_driver/lib.rs
index d08fb2b313ef6776dde2c2a2ed1486cfbb1f2499..3292b2e026bc70da9f3d8ea8522eff275eb30ad7 100644
--- a/src/librustc_driver/lib.rs
+++ b/src/librustc_driver/lib.rs
@@ -14,6 +14,8 @@
 //!
 //! This API is completely unstable and subject to change.
 
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "rustc_driver"]
 #![unstable(feature = "rustc_private")]
 #![staged_api]
diff --git a/src/librustc_lint/lib.rs b/src/librustc_lint/lib.rs
index 9eef0f1cf8b0ff75c84f50b60b71fcf687de1447..9781e9944f6427dee635f089a4c9a76e1f9324e1 100644
--- a/src/librustc_lint/lib.rs
+++ b/src/librustc_lint/lib.rs
@@ -19,6 +19,8 @@
 //!
 //! This API is completely unstable and subject to change.
 
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "rustc_lint"]
 #![unstable(feature = "rustc_private")]
 #![staged_api]
diff --git a/src/librustc_llvm/lib.rs b/src/librustc_llvm/lib.rs
index 09a187befb2130ec01ccb05fb84f16265d300e86..8f6ad343317099a69d6df7a92eb3e196c5f5996e 100644
--- a/src/librustc_llvm/lib.rs
+++ b/src/librustc_llvm/lib.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![allow(non_upper_case_globals)]
 #![allow(non_camel_case_types)]
 #![allow(non_snake_case)]
diff --git a/src/librustc_privacy/lib.rs b/src/librustc_privacy/lib.rs
index 46729988bb6bd976c658bb1c23e4be691c0e8c38..859e4ab28580fb013dd2a84c7f4cd04fcdf3e400 100644
--- a/src/librustc_privacy/lib.rs
+++ b/src/librustc_privacy/lib.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "rustc_privacy"]
 #![unstable(feature = "rustc_private")]
 #![staged_api]
diff --git a/src/librustc_resolve/lib.rs b/src/librustc_resolve/lib.rs
index 78ce9abe07d92495d9e646a2ae0122845b24231f..7724f4253b74b16d7e77d3236597b1f466936641 100644
--- a/src/librustc_resolve/lib.rs
+++ b/src/librustc_resolve/lib.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "rustc_resolve"]
 #![unstable(feature = "rustc_private")]
 #![staged_api]
diff --git a/src/librustc_trans/lib.rs b/src/librustc_trans/lib.rs
index 71317d5875b84fcdb1d3351632dfd0fa0dae1c06..5ccd7f61e01d676411ca3802ff416e71564f4d55 100644
--- a/src/librustc_trans/lib.rs
+++ b/src/librustc_trans/lib.rs
@@ -14,6 +14,8 @@
 //!
 //! This API is completely unstable and subject to change.
 
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "rustc_trans"]
 #![unstable(feature = "rustc_private")]
 #![staged_api]
diff --git a/src/librustc_typeck/lib.rs b/src/librustc_typeck/lib.rs
index 78dd66c8e7dbbd02e80bc8f197f2d014a2bf990e..bbc64a54013b717b7dc11e8287f9da17180b425c 100644
--- a/src/librustc_typeck/lib.rs
+++ b/src/librustc_typeck/lib.rs
@@ -62,7 +62,8 @@
 This API is completely unstable and subject to change.
 
 */
-
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "rustc_typeck"]
 #![unstable(feature = "rustc_private")]
 #![staged_api]
diff --git a/src/librustdoc/lib.rs b/src/librustdoc/lib.rs
index e58239a82c603b2487570641ec122241fa96dc7c..cbf7adcbe9a8cef458f753b1316cec3f95f22e9c 100644
--- a/src/librustdoc/lib.rs
+++ b/src/librustdoc/lib.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "rustdoc"]
 #![unstable(feature = "rustdoc")]
 #![staged_api]
diff --git a/src/libserialize/lib.rs b/src/libserialize/lib.rs
index d476fd72abc3b03ea2f8cc8b729f8182fa78fad6..8d58ba99e13138268c3176989fc883a386eda668 100644
--- a/src/libserialize/lib.rs
+++ b/src/libserialize/lib.rs
@@ -14,6 +14,8 @@
 Core encoding and decoding interfaces.
 */
 
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "serialize"]
 #![unstable(feature = "rustc_private",
             reason = "deprecated in favor of rustc-serialize on crates.io")]
diff --git a/src/libstd/lib.rs b/src/libstd/lib.rs
index 7957bc35b76b5c3e90507df79c6b624e9b2c6326..73848a51c1e25ca78ff0c280ed7221725ef5825a 100644
--- a/src/libstd/lib.rs
+++ b/src/libstd/lib.rs
@@ -94,7 +94,8 @@
 //! to all code by default. [`macros`](macros/index.html) contains
 //! all the standard macros, such as `assert!`, `panic!`, `println!`,
 //! and `format!`, also available to all Rust code.
-
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "std"]
 #![stable(feature = "rust1", since = "1.0.0")]
 #![staged_api]
diff --git a/src/libsyntax/lib.rs b/src/libsyntax/lib.rs
index 7acbd10ef03d818476adbcde6be57f32121c134c..091f3be631ea75728a74acdcdd4d95e57aefc96d 100644
--- a/src/libsyntax/lib.rs
+++ b/src/libsyntax/lib.rs
@@ -14,6 +14,8 @@
 //!
 //! This API is completely unstable and subject to change.
 
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "syntax"]
 #![unstable(feature = "rustc_private")]
 #![staged_api]
diff --git a/src/libterm/lib.rs b/src/libterm/lib.rs
index 756d67b5db1e1a37212ee04f4e0a133d80ba856a..ed42c16f19a0e4a7c284b32f341a1918146981fe 100644
--- a/src/libterm/lib.rs
+++ b/src/libterm/lib.rs
@@ -38,6 +38,8 @@
 //! [win]: http://msdn.microsoft.com/en-us/library/windows/desktop/ms682010%28v=vs.85%29.aspx
 //! [ti]: https://en.wikipedia.org/wiki/Terminfo
 
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "term"]
 #![unstable(feature = "rustc_private",
             reason = "use the crates.io `term` library instead")]
diff --git a/src/libtest/lib.rs b/src/libtest/lib.rs
index a144904903e58e8f7ca2d7dfcdd3da4e3926288e..538c96cd63ca0afaf8127c91689fc31c561abeca 100644
--- a/src/libtest/lib.rs
+++ b/src/libtest/lib.rs
@@ -23,6 +23,8 @@
 // running tests while providing a base that other test frameworks may
 // build off of.
 
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "test"]
 #![unstable(feature = "test")]
 #![staged_api]
diff --git a/src/libunicode/lib.rs b/src/libunicode/lib.rs
index 791886be1ce5b6a6de76889ca83bc7d7f53a3f7e..2095b6921c840a437dd428727942e7d01c0dd507 100644
--- a/src/libunicode/lib.rs
+++ b/src/libunicode/lib.rs
@@ -20,6 +20,8 @@
 //! provide for basic string-related manipulations. This crate does not
 //! (yet) aim to provide a full set of Unicode tables.
 
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "unicode"]
 #![unstable(feature = "unicode")]
 #![feature(staged_api)]