diff --git a/src/bootstrap/sanity.rs b/src/bootstrap/sanity.rs
index d1b235f4691..df6378a970b 100644
--- a/src/bootstrap/sanity.rs
+++ b/src/bootstrap/sanity.rs
@@ -69,22 +69,21 @@ pub fn check(build: &mut Build) {
         need_cmd("git".as_ref());
     }
 
-    // We need cmake, but only if we're actually building LLVM
-    for host in build.config.host.iter() {
-        if let Some(config) = build.config.target_config.get(host) {
-            if config.llvm_config.is_some() {
-                continue
-            }
-        }
+    // We need cmake, but only if we're actually building LLVM or sanitizers.
+    let building_llvm = build.config.host.iter()
+        .filter_map(|host| build.config.target_config.get(host))
+        .any(|config| config.llvm_config.is_none());
+    if building_llvm || build.config.sanitizers {
         need_cmd("cmake".as_ref());
-        if build.config.ninja {
-            // Some Linux distros rename `ninja` to `ninja-build`.
-            // CMake can work with either binary name.
-            if have_cmd("ninja-build".as_ref()).is_none() {
-                need_cmd("ninja".as_ref());
-            }
+    }
+
+    // Ninja is currently only used for LLVM itself.
+    if building_llvm && build.config.ninja {
+        // Some Linux distros rename `ninja` to `ninja-build`.
+        // CMake can work with either binary name.
+        if have_cmd("ninja-build".as_ref()).is_none() {
+            need_cmd("ninja".as_ref());
         }
-        break
     }
 
     if build.config.python.is_none() {