diff --git a/config.toml.example b/config.toml.example
index 6e53d9b442f16..ecc3e0ef77ff0 100644
--- a/config.toml.example
+++ b/config.toml.example
@@ -258,6 +258,9 @@ changelog-seen = 2
 # Defaults to the Python interpreter used to execute x.py
 #python = "python"
 
+# Path to (or name of) the CMake 3 executable to build LLVM.
+#cmake = "cmake"
+
 # Force Cargo to check that Cargo.lock describes the precise dependency
 # set that all the Cargo.toml files create, instead of updating it.
 #locked-deps = false
diff --git a/src/bootstrap/config.rs b/src/bootstrap/config.rs
index d7c29f6900a53..6df43bab11517 100644
--- a/src/bootstrap/config.rs
+++ b/src/bootstrap/config.rs
@@ -185,6 +185,7 @@ pub struct Config {
     pub npm: Option<PathBuf>,
     pub gdb: Option<PathBuf>,
     pub python: Option<PathBuf>,
+    pub cmake: Option<PathBuf>,
     pub cargo_native_static: bool,
     pub configure_args: Vec<String>,
 
@@ -474,6 +475,7 @@ define_config! {
         nodejs: Option<String> = "nodejs",
         npm: Option<String> = "npm",
         python: Option<String> = "python",
+        cmake: Option<String> = "cmake",
         locked_deps: Option<bool> = "locked-deps",
         vendor: Option<bool> = "vendor",
         full_bootstrap: Option<bool> = "full-bootstrap",
@@ -793,6 +795,7 @@ impl Config {
         config.npm = build.npm.map(PathBuf::from);
         config.gdb = build.gdb.map(PathBuf::from);
         config.python = build.python.map(PathBuf::from);
+        config.cmake = build.cmake.map(PathBuf::from);
         config.submodules = build.submodules;
         set(&mut config.low_priority, build.low_priority);
         set(&mut config.compiler_docs, build.compiler_docs);
diff --git a/src/bootstrap/lib.rs b/src/bootstrap/lib.rs
index 59102ad9f50b8..b39950729a484 100644
--- a/src/bootstrap/lib.rs
+++ b/src/bootstrap/lib.rs
@@ -645,6 +645,9 @@ impl Build {
         unsafe {
             job::setup(self);
         }
+        if let Some(cmake) = self.config.cmake.as_ref() {
+            env::set_var("CMAKE", cmake); // https://docs.rs/cmake/0.1.48/src/cmake/lib.rs.html#515
+        }
 
         self.maybe_update_submodules();
 
diff --git a/src/bootstrap/sanity.rs b/src/bootstrap/sanity.rs
index c96e6f9a3678f..dc0a8b691d45b 100644
--- a/src/bootstrap/sanity.rs
+++ b/src/bootstrap/sanity.rs
@@ -92,10 +92,31 @@ pub fn check(build: &mut Build) {
                     .unwrap_or(true)
             })
             .any(|build_llvm_ourselves| build_llvm_ourselves);
-    let need_cmake = building_llvm || build.config.any_sanitizers_enabled();
-    if need_cmake {
-        cmd_finder.must_have("cmake");
-    }
+    let need_default_cmake = if building_llvm || build.config.any_sanitizers_enabled() {
+        let cmake_env_var = env::var_os("CMAKE");
+        if let Some(explicit_name) = build.config.cmake.take() {
+            if let Some(cmake_from_env) = cmake_env_var {
+                if explicit_name != cmake_from_env {
+                    eprintln!(
+                        "env var CMAKE = {cmake_from_env:?} != {explicit_name:?} from config.toml"
+                    )
+                }
+            }
+            build.config.cmake = cmd_finder.must_have(explicit_name).into();
+            None
+        } else {
+            // _very_ simplified version of getenv_target_os("CMAKE") from
+            // https://docs.rs/cmake/0.1.48/src/cmake/lib.rs.html#515
+            if let Some(cmake_from_env) = cmake_env_var {
+                cmd_finder.must_have(cmake_from_env)
+            } else {
+                cmd_finder.must_have("cmake")
+            }
+            .into()
+        }
+    } else {
+        None
+    };
 
     build.config.python = build
         .config
@@ -201,14 +222,17 @@ pub fn check(build: &mut Build) {
             }
         }
 
-        if need_cmake && target.contains("msvc") {
-            // 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"));
-            if !out.contains("Visual Studio") {
-                panic!(
-                    "
+        if target.contains("msvc") {
+            if let Some(ref cmake_path) =
+                need_default_cmake.as_ref().or(build.config.cmake.as_ref())
+            {
+                // 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_path).arg("--help"));
+                if !out.contains("Visual Studio") {
+                    panic!(
+                        "
 cmake does not support Visual Studio generators.
 
 This is likely due to it being an msys/cygwin build of cmake,
@@ -220,7 +244,8 @@ package instead of cmake:
 
 $ pacman -R cmake && pacman -S mingw-w64-x86_64-cmake
 "
-                );
+                    );
+                }
             }
         }
     }