diff --git a/src/bootstrap/bootstrap.py b/src/bootstrap/bootstrap.py
index d5efed61b541e..7d4ac93ea2397 100644
--- a/src/bootstrap/bootstrap.py
+++ b/src/bootstrap/bootstrap.py
@@ -66,7 +66,7 @@ def download(path, url, probably_big, verbose):
 def _download(path, url, probably_big, verbose, exception):
     if probably_big or verbose:
         print("downloading {}".format(url))
-    # see http://serverfault.com/questions/301128/how-to-download
+    # See http://serverfault.com/questions/301128/how-to-download.
     if sys.platform == 'win32':
         run(["PowerShell.exe", "/nologo", "-Command",
              "[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12;",
@@ -79,7 +79,7 @@ def _download(path, url, probably_big, verbose, exception):
         else:
             option = "-s"
         run(["curl", option,
-             "-y", "30", "-Y", "10",    # timeout if speed is < 10 bytes/sec for > 30 seconds
+             "-y", "30", "-Y", "10",     # timeout if speed is < 10 bytes/sec for > 30 seconds
              "--connect-timeout", "30",  # timeout if cannot connect within 30 seconds
              "--retry", "3", "-Sf", "-o", path, url],
             verbose=verbose,
@@ -131,7 +131,7 @@ def run(args, verbose=False, exception=False, **kwargs):
     if verbose:
         print("running: " + ' '.join(args))
     sys.stdout.flush()
-    # Use Popen here instead of call() as it apparently allows powershell on
+    # Use `Popen` here instead of `call()` as it apparently allows powershell on
     # Windows to not lock up waiting for input presumably.
     ret = subprocess.Popen(args, **kwargs)
     code = ret.wait()
@@ -660,6 +660,7 @@ def bootstrap_binary(self):
 
     def build_bootstrap(self):
         """Build bootstrap"""
+
         build_dir = os.path.join(self.build_dir, "bootstrap")
         if self.clean and os.path.exists(build_dir):
             shutil.rmtree(build_dir)
@@ -680,7 +681,7 @@ def build_bootstrap(self):
         env["LIBRARY_PATH"] = os.path.join(self.bin_root(), "lib") + \
             (os.pathsep + env["LIBRARY_PATH"]) \
             if "LIBRARY_PATH" in env else ""
-        # preserve existing RUSTFLAGS
+        # Preserve existing `RUSTFLAGS`.
         env.setdefault("RUSTFLAGS", "")
         env["RUSTFLAGS"] += " -Cdebuginfo=2"
 
@@ -748,7 +749,7 @@ def update_submodule(self, module, checked_out, recorded_submodules):
                  "--init", "--recursive", "--progress", module],
                 cwd=self.rust_root, verbose=self.verbose, exception=True)
         except RuntimeError:
-            # Some versions of git don't support --progress.
+            # Some versions of Git don't support `--progress`.
             run(["git", "submodule", "update",
                  "--init", "--recursive", module],
                 cwd=self.rust_root, verbose=self.verbose)
@@ -763,7 +764,7 @@ def update_submodules(self):
                 self.get_toml('submodules') == "false":
             return
 
-        # check the existence of 'git' command
+        # Check for the existence of the `git` executable.
         try:
             subprocess.check_output(['git', '--version'])
         except (subprocess.CalledProcessError, OSError):
@@ -878,7 +879,7 @@ def bootstrap(help_triggered):
     args = [a for a in sys.argv if a != '-h' and a != '--help']
     args, _ = parser.parse_known_args(args)
 
-    # Configure initial bootstrap
+    # Configure initial bootstrap.
     build = RustBuild()
     build.rust_root = args.src or os.path.abspath(os.path.join(__file__, '../../..'))
     build.verbose = args.verbose
@@ -944,7 +945,7 @@ def main():
     """Entry point for the bootstrap process"""
     start_time = time()
 
-    # x.py help <cmd> ...
+    # `x.py help <cmd> ...`
     if len(sys.argv) > 1 and sys.argv[1] == 'help':
         sys.argv = [sys.argv[0], '-h'] + sys.argv[2:]
 
diff --git a/src/bootstrap/sanity.rs b/src/bootstrap/sanity.rs
index 1760d655b3b4e..64e417bc2588b 100644
--- a/src/bootstrap/sanity.rs
+++ b/src/bootstrap/sanity.rs
@@ -1,4 +1,4 @@
-//! Sanity checking performed by rustbuild before actually executing anything.
+//! Sanity-checking performed by rustbuild before actually executing anything.
 //!
 //! This module contains the implementation of ensuring that the build
 //! environment looks reasonable before progressing. This will verify that
@@ -41,10 +41,10 @@ impl Finder {
                     let mut cmd_exe = cmd.clone();
                     cmd_exe.push(".exe");
 
-                    if target.is_file()                   // some/path/git
-                    || path.join(&cmd_exe).exists()   // some/path/git.exe
+                    if target.is_file()               // `some/path/git`
+                    || path.join(&cmd_exe).exists()   // `some/path/git.exe`
                     || target.join(&cmd_exe).exists()
-                    // some/path/git/git.exe
+                    // `some/path/git/git.exe`
                     {
                         return Some(target);
                     }
@@ -68,7 +68,7 @@ pub fn check(build: &mut Build) {
     // being unable to identify the files properly. See
     // https://github.com/rust-lang/rust/issues/34959 for more details.
     if cfg!(windows) && path.to_string_lossy().contains('\"') {
-        panic!("PATH contains invalid character '\"'");
+        panic!("`PATH` contains invalid character '\"'");
     }
 
     let mut cmd_finder = Finder::new();
@@ -78,7 +78,7 @@ pub fn check(build: &mut Build) {
         cmd_finder.must_have("git");
     }
 
-    // We need cmake, but only if we're actually building LLVM or sanitizers.
+    // We need CMake, but only if we're actually building LLVM or sanitizers.
     let building_llvm = build
         .hosts
         .iter()
@@ -92,7 +92,17 @@ pub fn check(build: &mut Build) {
         })
         .any(|build_llvm_ourselves| build_llvm_ourselves);
     if building_llvm || build.config.sanitizers {
-        cmd_finder.must_have("cmake");
+        // Choose CMake executable with the following priority:
+        // 1. `CMAKE` env var, if set.
+        // 2. `cmake3`, if it exists.
+        // 3. `cmake`.
+        if let Some(cmake_path) = env::var_os("CMAKE") {
+            cmd_finder.must_have(cmake_path);
+        } else if cmd_finder.maybe_have("cmake3").is_some() {
+            env::set_var("CMAKE", "cmake3");
+        } else {
+            cmd_finder.must_have("cmake");
+        }
     }
 
     // Ninja is currently only used for LLVM itself.
@@ -105,7 +115,7 @@ pub fn check(build: &mut Build) {
             }
         }
 
-        // If ninja isn't enabled but we're building for MSVC then we try
+        // If Ninja isn't enabled but we're building for MSVC then we try
         // doubly hard to enable it. It was realized in #43767 that the msbuild
         // CMake generator for MSVC doesn't respect configuration options like
         // disabling LLVM assertions, which can often be quite important!
@@ -182,7 +192,7 @@ pub fn check(build: &mut Build) {
     // Externally configured LLVM requires FileCheck to exist
     let filecheck = build.llvm_filecheck(build.build);
     if !filecheck.starts_with(&build.out) && !filecheck.exists() && build.config.codegen_tests {
-        panic!("FileCheck executable {:?} does not exist", filecheck);
+        panic!("FileCheck executable `{:?}` does not exist", filecheck);
     }
 
     for target in &build.targets {
@@ -210,13 +220,16 @@ pub fn check(build: &mut Build) {
             match build.musl_root(*target) {
                 Some(root) => {
                     if fs::metadata(root.join("lib/libc.a")).is_err() {
-                        panic!("couldn't find libc.a in musl dir: {}", root.join("lib").display());
+                        panic!(
+                            "couldn't find `libc.a` in musl dir: {}",
+                            root.join("lib").display()
+                        );
                     }
                 }
                 None => panic!(
-                    "when targeting MUSL either the rust.musl-root \
-                            option or the target.$TARGET.musl-root option must \
-                            be specified in config.toml"
+                    "when targeting MUSL, either the `rust.musl-root` \
+                     option or the `target.$TARGET.musl-root` option must \
+                     be specified in `config.toml`"
                 ),
             }
         }
@@ -225,7 +238,8 @@ pub fn check(build: &mut Build) {
             // There are three builds of cmake on windows: MSVC, MinGW, and
             // Cygwin. The Cygwin build does not have generators for Visual
             // Studio, so detect that here and error.
-            let out = output(Command::new("cmake").arg("--help"));
+            let cmake_path = env::var("CMAKE").unwrap_or("cmake".into());
+            let out = output(Command::new(cmake_path).arg("--help"));
             if !out.contains("Visual Studio") {
                 panic!(
                     "
@@ -254,7 +268,7 @@ $ pacman -R cmake && pacman -S mingw-w64-x86_64-cmake
         if stage0.contains("\ndev:") {
             panic!(
                 "bootstrapping from a dev compiler in a stable release, but \
-                    should only be bootstrapping from a released compiler!"
+                 should only be bootstrapping from a released compiler!"
             );
         }
     }