From 1c9f999157e40b770c60518174355273875bf88d Mon Sep 17 00:00:00 2001
From: Matthew Healy <matthew.healy@soundcloud.com>
Date: Thu, 9 Jan 2020 22:19:33 +0100
Subject: [PATCH 1/3] Add llvm-skip-rebuild to opts

---
 src/bootstrap/flags.rs | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/bootstrap/flags.rs b/src/bootstrap/flags.rs
index ffc24367db6..813e89eef38 100644
--- a/src/bootstrap/flags.rs
+++ b/src/bootstrap/flags.rs
@@ -150,6 +150,14 @@ To learn more about a subcommand, run `./x.py <subcommand> -h`",
             "VALUE",
         );
         opts.optopt("", "error-format", "rustc error format", "FORMAT");
+        opts.optopt(
+            "",
+            "llvm-skip-rebuild",
+            "whether rebuilding llvm should be skipped \
+             a VALUE of TRUE indicates that llvm will not be rebuilt \
+             VALUE overrides the skip-rebuild option in config.toml.",
+            "VALUE",
+        );
 
         // fn usage()
         let usage =

From 0bbbd5d418f764146afdde3460c170db205ba0fa Mon Sep 17 00:00:00 2001
From: Matthew Healy <matthew.healy@soundcloud.com>
Date: Thu, 9 Jan 2020 22:51:38 +0100
Subject: [PATCH 2/3] Match llvm-skip-rebuild flag

---
 src/bootstrap/flags.rs | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/bootstrap/flags.rs b/src/bootstrap/flags.rs
index 813e89eef38..1fbdd50a511 100644
--- a/src/bootstrap/flags.rs
+++ b/src/bootstrap/flags.rs
@@ -38,6 +38,8 @@ pub struct Flags {
     //
     // true => deny, false => warn
     pub deny_warnings: Option<bool>,
+
+    pub llvm_skip_rebuild: Option<bool>,
 }
 
 pub enum Subcommand {
@@ -495,6 +497,9 @@ Arguments:
                 .map(|p| p.into())
                 .collect::<Vec<_>>(),
             deny_warnings: parse_deny_warnings(&matches),
+            llvm_skip_rebuild: matches.opt_str("llvm-skip-rebuild").map(|s| s.to_lowercase()).map(
+                |s| s.parse::<bool>().expect("`llvm-skip-rebuild` should be either true or false"),
+            ),
         }
     }
 }

From 7e50b599bfeb75f7be1d5a1fa855e37ec6d0e65d Mon Sep 17 00:00:00 2001
From: Matthew Healy <matthew.healy@soundcloud.com>
Date: Thu, 9 Jan 2020 23:13:57 +0100
Subject: [PATCH 3/3] Prefer llvm-skip-rebuild flag value over config.toml

---
 src/bootstrap/config.rs | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/bootstrap/config.rs b/src/bootstrap/config.rs
index 944df66431f..110c8b844d5 100644
--- a/src/bootstrap/config.rs
+++ b/src/bootstrap/config.rs
@@ -493,9 +493,13 @@ impl Config {
             config.mandir = install.mandir.clone().map(PathBuf::from);
         }
 
+        // We want the llvm-skip-rebuild flag to take precedence over the
+        // skip-rebuild config.toml option so we store it separately
+        // so that we can infer the right value
+        let mut llvm_skip_rebuild = flags.llvm_skip_rebuild;
+
         // Store off these values as options because if they're not provided
         // we'll infer default values for them later
-        let mut llvm_skip_rebuild = None;
         let mut llvm_assertions = None;
         let mut debug = None;
         let mut debug_assertions = None;
@@ -517,7 +521,7 @@ impl Config {
             }
             set(&mut config.ninja, llvm.ninja);
             llvm_assertions = llvm.assertions;
-            llvm_skip_rebuild = llvm.skip_rebuild;
+            llvm_skip_rebuild = llvm_skip_rebuild.or(llvm.skip_rebuild);
             set(&mut config.llvm_optimize, llvm.optimize);
             set(&mut config.llvm_thin_lto, llvm.thin_lto);
             set(&mut config.llvm_release_debuginfo, llvm.release_debuginfo);