diff --git a/src/bootstrap/check.rs b/src/bootstrap/check.rs
index 385376333c1d..b45849972b07 100644
--- a/src/bootstrap/check.rs
+++ b/src/bootstrap/check.rs
@@ -245,6 +245,9 @@ pub fn compiletest(build: &Build,
     let llvm_config = build.llvm_config(target);
     let llvm_version = output(Command::new(&llvm_config).arg("--version"));
     cmd.arg("--llvm-version").arg(llvm_version);
+    if !build.is_rust_llvm(target) {
+        cmd.arg("--system-llvm");
+    }
 
     cmd.args(&build.flags.cmd.test_args());
 
diff --git a/src/llvm b/src/llvm
index 84c52ce9b75d..ee545e1d13e6 160000
--- a/src/llvm
+++ b/src/llvm
@@ -1 +1 @@
-Subproject commit 84c52ce9b75d841629e6f821b3794998fb0ddbd9
+Subproject commit ee545e1d13e6f2191572aebcadb7d1640ce45c65
diff --git a/src/test/codegen/alloc-optimisation.rs b/src/test/codegen/alloc-optimisation.rs
index 3953f637cf7a..07dc1350714b 100644
--- a/src/test/codegen/alloc-optimisation.rs
+++ b/src/test/codegen/alloc-optimisation.rs
@@ -7,17 +7,11 @@
 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
+//
+// no-system-llvm
+// compile-flags: -O
 #![crate_type="lib"]
 
-#[no_mangle]
-pub fn alloc_zeroed_test(size: u8) {
-    // CHECK-LABEL: @alloc_zeroed_test
-    // CHECK-NEXT: start:
-    // CHECK-NEXT: ret void
-    let x = vec![0u8; size as usize];
-    drop(x);
-}
-
 #[no_mangle]
 pub fn alloc_test(data: u32) {
     // CHECK-LABEL: @alloc_test
diff --git a/src/tools/compiletest/src/common.rs b/src/tools/compiletest/src/common.rs
index 92f6f36d69d9..cc95e1b89305 100644
--- a/src/tools/compiletest/src/common.rs
+++ b/src/tools/compiletest/src/common.rs
@@ -166,6 +166,9 @@ pub struct Config {
     // Version of LLVM
     pub llvm_version: Option<String>,
 
+    // Is LLVM a system LLVM
+    pub system_llvm: bool,
+
     // Path to the android tools
     pub android_cross_path: PathBuf,
 
diff --git a/src/tools/compiletest/src/header.rs b/src/tools/compiletest/src/header.rs
index c503ca7d8cd1..aa33580b337c 100644
--- a/src/tools/compiletest/src/header.rs
+++ b/src/tools/compiletest/src/header.rs
@@ -166,6 +166,9 @@ impl EarlyProps {
         }
 
         fn ignore_llvm(config: &Config, line: &str) -> bool {
+            if config.system_llvm && line.starts_with("no-system-llvm") {
+                    return true;
+            }
             if let Some(ref actual_version) = config.llvm_version {
                 if line.starts_with("min-llvm-version") {
                     let min_version = line.trim_right()
diff --git a/src/tools/compiletest/src/main.rs b/src/tools/compiletest/src/main.rs
index 1bb0b765f9f1..3dac580a5f4b 100644
--- a/src/tools/compiletest/src/main.rs
+++ b/src/tools/compiletest/src/main.rs
@@ -97,6 +97,7 @@ pub fn parse_config(args: Vec<String> ) -> Config {
           optopt("", "gdb", "path to GDB to use for GDB debuginfo tests", "PATH"),
           optopt("", "lldb-version", "the version of LLDB used", "VERSION STRING"),
           optopt("", "llvm-version", "the version of LLVM used", "VERSION STRING"),
+          optflag("", "system-llvm", "is LLVM the system LLVM"),
           optopt("", "android-cross-path", "Android NDK standalone path", "PATH"),
           optopt("", "adb-path", "path to the android debugger", "PATH"),
           optopt("", "adb-test-dir", "path to tests for the android debugger", "PATH"),
@@ -183,6 +184,7 @@ pub fn parse_config(args: Vec<String> ) -> Config {
         gdb_native_rust: gdb_native_rust,
         lldb_version: extract_lldb_version(matches.opt_str("lldb-version")),
         llvm_version: matches.opt_str("llvm-version"),
+        system_llvm: matches.opt_present("system-llvm"),
         android_cross_path: opt_path(matches, "android-cross-path"),
         adb_path: opt_str2(matches.opt_str("adb-path")),
         adb_test_dir: opt_str2(matches.opt_str("adb-test-dir")),