diff --git a/library/std/src/sys/thread_local/native/mod.rs b/library/std/src/sys/thread_local/native/mod.rs
index 209a8790def08..ce039242b8983 100644
--- a/library/std/src/sys/thread_local/native/mod.rs
+++ b/library/std/src/sys/thread_local/native/mod.rs
@@ -81,9 +81,10 @@ pub macro thread_local_inner {
 
     // used to generate the `LocalKey` value for `thread_local!`
     (@key $t:ty, $(#[$align_attr:meta])*, $init:expr) => {{
-        // We intentionally have an argument-position `'static` lifetime so that elided lifetimes in `$t`
-        // become `'static` like they do for `const`s and `static`s, including in the other two
-        // `thread_local!` implementations.
+        // NOTE: The `PhantomData` here is a nice trick to ensure that *all* usages of `$t` can be
+        // inferred to have static lifetimes. This function definition would normally *not* be such
+        // a definition, but because lifetime elision tends to prefer lifetimes matching arguments
+        // to a function, the `'static` lifetime inside the `PhantomData` qualifies here.
         #[allow(mismatched_lifetime_syntaxes)]
         #[inline]
         fn __rust_std_internal_init_fn(_lifetime_elision: $crate::marker::PhantomData<&'static ()>) -> $t {
@@ -92,10 +93,12 @@ pub macro thread_local_inner {
 
         unsafe {
             $crate::thread::LocalKey::new(const {
+                // NOTE: `$t`'s lifetimes can always be inferred in turbofish position
                 if $crate::mem::needs_drop::<$t>() {
                     |__rust_std_internal_init| {
                         #[thread_local]
                         $(#[$align_attr])*
+                        // NOTE: `$t`'s lifetimes can always be inferred `'static` for `static`s
                         static __RUST_STD_INTERNAL_VAL: $crate::thread::local_impl::LazyStorage<$t, ()>
                             = $crate::thread::local_impl::LazyStorage::new();
                         __RUST_STD_INTERNAL_VAL.get_or_init(__rust_std_internal_init, || __rust_std_internal_init_fn($crate::marker::PhantomData))
@@ -104,6 +107,7 @@ pub macro thread_local_inner {
                     |__rust_std_internal_init| {
                         #[thread_local]
                         $(#[$align_attr])*
+                        // NOTE: `$t`'s lifetimes can always be inferred `'static` for `static`s
                         static __RUST_STD_INTERNAL_VAL: $crate::thread::local_impl::LazyStorage<$t, !>
                             = $crate::thread::local_impl::LazyStorage::new();
                         __RUST_STD_INTERNAL_VAL.get_or_init(__rust_std_internal_init, || __rust_std_internal_init_fn($crate::marker::PhantomData))
diff --git a/library/std/src/sys/thread_local/os.rs b/library/std/src/sys/thread_local/os.rs
index 8588fc994350b..48526169e3d5a 100644
--- a/library/std/src/sys/thread_local/os.rs
+++ b/library/std/src/sys/thread_local/os.rs
@@ -20,9 +20,10 @@ pub macro thread_local_inner {
 
     // used to generate the `LocalKey` value for `thread_local!`.
     (@key $t:ty, $($(#[$($align_attr:tt)*])+)?, $init:expr) => {{
-        // We intentionally have an argument-position `'static` lifetime so that elided lifetimes in `$t`
-        // become `'static` like they do for `const`s and `static`s, including in the other two
-        // `thread_local!` implementations.
+        // NOTE: The `PhantomData` here is a nice trick to ensure that *all* usages of `$t` can be
+        // inferred to have static lifetimes. This function definition would normally *not* be such
+        // a definition, but because lifetime elision tends to prefer lifetimes matching arguments
+        // to a function, the `'static` lifetime inside the `PhantomData` qualifies here.
         #[allow(mismatched_lifetime_syntaxes)]
         #[inline]
         fn __rust_std_internal_init_fn(_lifetime_elision: $crate::marker::PhantomData<&'static ()>) -> $t { $init }
@@ -32,6 +33,7 @@ pub macro thread_local_inner {
         // in `tests/thread.rs` if these types are renamed.
         unsafe {
             $crate::thread::LocalKey::new(|__rust_std_internal_init| {
+                // NOTE: `$t`'s lifetimes can always be inferred `'static` for `static`s
                 static __RUST_STD_INTERNAL_VAL: $crate::thread::local_impl::Storage<$t, {
                     $({
                         // Ensure that attributes have valid syntax
@@ -42,6 +44,7 @@ pub macro thread_local_inner {
                     })?
 
                     #[allow(unused_mut)]
+                    // NOTE: `$t`'s lifetimes can always be inferred in turbofish position
                     let mut final_align = $crate::thread::local_impl::value_align::<$t>();
                     $($($crate::thread::local_impl::thread_local_inner!(@align final_align, $($align_attr)*);)+)?
                     final_align
diff --git a/tests/ui/thread-local/non-static-lifetimes.rs b/tests/ui/thread-local/non-static-lifetimes.rs
new file mode 100644
index 0000000000000..bd87acb6d49d2
--- /dev/null
+++ b/tests/ui/thread-local/non-static-lifetimes.rs
@@ -0,0 +1,18 @@
+use std::borrow::Cow;
+
+fn main() {
+    let x = "";
+    std::thread_local!(static A: &str = x);
+    //~^ ERROR attempt to use a non-constant value in a constant [E0435]
+}
+
+fn test<'a>(x: &'a str) {
+    std::thread_local!(static A: Cow<'a, str> = Cow::Borrowed(""));
+    //~^ ERROR can't use generic parameters from outer item [E0401]
+    //~| ERROR can't use generic parameters from outer item [E0401]
+    //~| ERROR can't use generic parameters from outer item [E0401]
+    //~| ERROR can't use generic parameters from outer item [E0401]
+    //~| ERROR can't use generic parameters from outer item [E0401]
+
+    // wow, aren't macros great?
+}
diff --git a/tests/ui/thread-local/non-static-lifetimes.stderr b/tests/ui/thread-local/non-static-lifetimes.stderr
new file mode 100644
index 0000000000000..5f9a0d6889fda
--- /dev/null
+++ b/tests/ui/thread-local/non-static-lifetimes.stderr
@@ -0,0 +1,61 @@
+error[E0435]: attempt to use a non-constant value in a constant
+  --> $DIR/non-static-lifetimes.rs:5:41
+   |
+LL |     std::thread_local!(static A: &str = x);
+   |                               -         ^
+   |                               |
+   |                               this would need to be a `let`
+
+error[E0401]: can't use generic parameters from outer item
+  --> $DIR/non-static-lifetimes.rs:10:38
+   |
+LL | fn test<'a>(x: &'a str) {
+   |         -- lifetime parameter from outer item
+LL |     std::thread_local!(static A: Cow<'a, str> = Cow::Borrowed(""));
+   |                                      ^^ use of generic parameter from outer item
+
+error[E0401]: can't use generic parameters from outer item
+  --> $DIR/non-static-lifetimes.rs:10:38
+   |
+LL | fn test<'a>(x: &'a str) {
+   |         -- lifetime parameter from outer item
+LL |     std::thread_local!(static A: Cow<'a, str> = Cow::Borrowed(""));
+   |     ---------------------------------^^---------------------------
+   |     |                                |
+   |     |                                use of generic parameter from outer item
+   |     lifetime `'a` is missing in item created through this procedural macro
+
+error[E0401]: can't use generic parameters from outer item
+  --> $DIR/non-static-lifetimes.rs:10:38
+   |
+LL | fn test<'a>(x: &'a str) {
+   |         -- lifetime parameter from outer item
+LL |     std::thread_local!(static A: Cow<'a, str> = Cow::Borrowed(""));
+   |                                      ^^ use of generic parameter from outer item
+   |
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error[E0401]: can't use generic parameters from outer item
+  --> $DIR/non-static-lifetimes.rs:10:38
+   |
+LL | fn test<'a>(x: &'a str) {
+   |         -- lifetime parameter from outer item
+LL |     std::thread_local!(static A: Cow<'a, str> = Cow::Borrowed(""));
+   |                                      ^^ use of generic parameter from outer item
+   |
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error[E0401]: can't use generic parameters from outer item
+  --> $DIR/non-static-lifetimes.rs:10:38
+   |
+LL | fn test<'a>(x: &'a str) {
+   |         -- lifetime parameter from outer item
+LL |     std::thread_local!(static A: Cow<'a, str> = Cow::Borrowed(""));
+   |                                      ^^ use of generic parameter from outer item
+   |
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error: aborting due to 6 previous errors
+
+Some errors have detailed explanations: E0401, E0435.
+For more information about an error, try `rustc --explain E0401`.