3 files changed, 8 insertions, 1 deletions
diff --git a/src/bootstrap/defaults/config.dist.toml b/src/bootstrap/defaults/config.dist.toml
index 4346a9c2dd1..d4feffe0227 100644
--- a/src/bootstrap/defaults/config.dist.toml
+++ b/src/bootstrap/defaults/config.dist.toml
@@ -11,7 +11,6 @@ extended = true
 # Most users installing from source want to build all parts of the project from source.
 [llvm]
 download-ci-llvm = false
-
 [rust]
 # We have several defaults in bootstrap that depend on whether the channel is `dev` (e.g. `omit-git-hash` and `download-ci-llvm`).
 # Make sure they don't get set when installing from source.
diff --git a/src/bootstrap/defaults/config.library.toml b/src/bootstrap/defaults/config.library.toml
index 5447565a4b0..3d697be8156 100644
--- a/src/bootstrap/defaults/config.library.toml
+++ b/src/bootstrap/defaults/config.library.toml
@@ -8,6 +8,9 @@ bench-stage = 0
 [rust]
 # This greatly increases the speed of rebuilds, especially when there are only minor changes. However, it makes the initial build slightly slower.
 incremental = true
+# Download rustc from CI instead of building it from source.
+# For stage > 1 builds, this cuts compile times significantly when there are no changes on "compiler" tree.
+download-rustc = "if-unchanged"
 # Make the compiler and standard library faster to build, at the expense of a ~20% runtime slowdown.
 lto = "off"
 
diff --git a/src/bootstrap/defaults/config.tools.toml b/src/bootstrap/defaults/config.tools.toml
index 76b47a841b3..27c1d1cf26d 100644
--- a/src/bootstrap/defaults/config.tools.toml
+++ b/src/bootstrap/defaults/config.tools.toml
@@ -3,6 +3,11 @@
 [rust]
 # This greatly increases the speed of rebuilds, especially when there are only minor changes. However, it makes the initial build slightly slower.
 incremental = true
+# Download rustc from CI instead of building it from source.
+# For stage > 1 builds, this cuts compile times significantly when there are no changes on "compiler" tree.
+# Using these defaults will download the stage2 compiler (see `download-rustc`
+# setting) and the stage2 toolchain should therefore be used for these defaults.
+download-rustc = "if-unchanged"
 
 [build]
 # Document with the in-tree rustdoc by default, since `download-rustc` makes it quick to compile.