diff --git a/src/bootstrap/config/tests.rs b/src/bootstrap/config/tests.rs
index 681ecbfeb5b8f..5a105007f21fc 100644
--- a/src/bootstrap/config/tests.rs
+++ b/src/bootstrap/config/tests.rs
@@ -11,6 +11,11 @@ fn parse(config: &str) -> Config {
 
 #[test]
 fn download_ci_llvm() {
+    if crate::native::is_ci_llvm_modified(&parse("")) {
+        eprintln!("Detected LLVM as non-available: running in CI and modified LLVM in this change");
+        return;
+    }
+
     let parse_llvm = |s| parse(s).llvm_from_ci;
     let if_available = parse_llvm("llvm.download-ci-llvm = \"if-available\"");
 
diff --git a/src/bootstrap/native.rs b/src/bootstrap/native.rs
index 21157b02a78ef..5987b641b3927 100644
--- a/src/bootstrap/native.rs
+++ b/src/bootstrap/native.rs
@@ -216,21 +216,24 @@ pub(crate) fn is_ci_llvm_available(config: &Config, asserts: bool) -> bool {
         }
     }
 
-    if CiEnv::is_ci() {
+    if is_ci_llvm_modified(config) {
+        eprintln!("Detected LLVM as non-available: running in CI and modified LLVM in this change");
+        return false;
+    }
+
+    true
+}
+
+/// Returns true if we're running in CI with modified LLVM (and thus can't download it)
+pub(crate) fn is_ci_llvm_modified(config: &Config) -> bool {
+    CiEnv::is_ci() && {
         // We assume we have access to git, so it's okay to unconditionally pass
         // `true` here.
         let llvm_sha = detect_llvm_sha(config, true);
         let head_sha = output(config.git().arg("rev-parse").arg("HEAD"));
         let head_sha = head_sha.trim();
-        if llvm_sha == head_sha {
-            eprintln!(
-                "Detected LLVM as non-available: running in CI and modified LLVM in this change"
-            );
-            return false;
-        }
+        llvm_sha == head_sha
     }
-
-    true
 }
 
 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
diff --git a/src/llvm-project b/src/llvm-project
index 477e7285b12f8..fd949f3034f8a 160000
--- a/src/llvm-project
+++ b/src/llvm-project
@@ -1 +1 @@
-Subproject commit 477e7285b12f876ad105188cfcfc8adda7dc29aa
+Subproject commit fd949f3034f8a422ecfffa889c2823485dde4bdd
diff --git a/tests/ui/numbers-arithmetic/issue-105626.rs b/tests/ui/numbers-arithmetic/issue-105626.rs
new file mode 100644
index 0000000000000..f97edd510c9e6
--- /dev/null
+++ b/tests/ui/numbers-arithmetic/issue-105626.rs
@@ -0,0 +1,17 @@
+// run-pass
+// only-x86
+// min-system-llvm-version: 16
+// compile-flags: -Ctarget-feature=+sse2
+
+use std::hint::black_box;
+
+fn main() {
+    let n: i64 = black_box(0x3fffffdfffffff);
+    let r = f32::from_bits(0x5a7fffff);
+
+    assert_ne!((n as f64) as f32, n as f32);
+
+    // FIXME: these assertions fail if only x87 is enabled
+    assert_eq!(n as i64 as f32, r);
+    assert_eq!(n as u64 as f32, r);
+}