diff --git a/src/doc/unstable-book/src/language-features/lang-items.md b/src/doc/unstable-book/src/language-features/lang-items.md
index 6a7aea7f1c2..bac619fd4a3 100644
--- a/src/doc/unstable-book/src/language-features/lang-items.md
+++ b/src/doc/unstable-book/src/language-features/lang-items.md
@@ -19,6 +19,7 @@ sugar for dynamic allocations via `malloc` and `free`:
 #![feature(lang_items, box_syntax, start, libc, core_intrinsics)]
 #![no_std]
 use core::intrinsics;
+use core::panic::PanicInfo;
 
 extern crate libc;
 
@@ -50,7 +51,7 @@ fn main(_argc: isize, _argv: *const *const u8) -> isize {
 }
 
 #[lang = "eh_personality"] extern fn rust_eh_personality() {}
-#[lang = "panic_fmt"] extern fn rust_begin_panic() -> ! { unsafe { intrinsics::abort() } }
+#[lang = "panic_impl"] extern fn rust_begin_panic(info: &PanicInfo) -> ! { unsafe { intrinsics::abort() } }
 #[lang = "eh_unwind_resume"] extern fn rust_eh_unwind_resume() {}
 #[no_mangle] pub extern fn rust_eh_register_frames () {}
 #[no_mangle] pub extern fn rust_eh_unregister_frames () {}
@@ -110,6 +111,7 @@ in the same format as C:
 #![feature(start)]
 #![no_std]
 use core::intrinsics;
+use core::panic::PanicInfo;
 
 // Pull in the system libc library for what crt0.o likely requires.
 extern crate libc;
@@ -134,12 +136,9 @@ pub extern fn rust_eh_personality() {
 pub extern fn rust_eh_unwind_resume() {
 }
 
-#[lang = "panic_fmt"]
+#[lang = "panic_impl"]
 #[no_mangle]
-pub extern fn rust_begin_panic(_msg: core::fmt::Arguments,
-                               _file: &'static str,
-                               _line: u32,
-                               _column: u32) -> ! {
+pub extern fn rust_begin_panic(info: &PanicInfo) -> ! {
     unsafe { intrinsics::abort() }
 }
 ```
@@ -155,6 +154,7 @@ compiler's name mangling too:
 #![no_std]
 #![no_main]
 use core::intrinsics;
+use core::panic::PanicInfo;
 
 // Pull in the system libc library for what crt0.o likely requires.
 extern crate libc;
@@ -179,12 +179,9 @@ pub extern fn rust_eh_personality() {
 pub extern fn rust_eh_unwind_resume() {
 }
 
-#[lang = "panic_fmt"]
+#[lang = "panic_impl"]
 #[no_mangle]
-pub extern fn rust_begin_panic(_msg: core::fmt::Arguments,
-                               _file: &'static str,
-                               _line: u32,
-                               _column: u32) -> ! {
+pub extern fn rust_begin_panic(info: &PanicInfo) -> ! {
     unsafe { intrinsics::abort() }
 }
 ```
@@ -215,7 +212,7 @@ called. The language item's name is `eh_personality`.
 
 The second function, `rust_begin_panic`, is also used by the failure mechanisms of the
 compiler. When a panic happens, this controls the message that's displayed on
-the screen. While the language item's name is `panic_fmt`, the symbol name is
+the screen. While the language item's name is `panic_impl`, the symbol name is
 `rust_begin_panic`.
 
 A third function, `rust_eh_unwind_resume`, is also needed if the `custom_unwind_resume`
@@ -259,8 +256,8 @@ the source code.
   - `msvc_try_filter`: `libpanic_unwind/seh.rs` (SEH)
   - `panic`: `libcore/panicking.rs`
   - `panic_bounds_check`: `libcore/panicking.rs`
-  - `panic_fmt`: `libcore/panicking.rs`
-  - `panic_fmt`: `libstd/panicking.rs`
+  - `panic_impl`: `libcore/panicking.rs`
+  - `panic_impl`: `libstd/panicking.rs`
 - Allocations
   - `owned_box`: `liballoc/boxed.rs`
   - `exchange_malloc`: `liballoc/heap.rs`
diff --git a/src/doc/unstable-book/src/language-features/used.md b/src/doc/unstable-book/src/language-features/used.md
index 75a8b2774f4..c3b7f2e41e1 100644
--- a/src/doc/unstable-book/src/language-features/used.md
+++ b/src/doc/unstable-book/src/language-features/used.md
@@ -87,11 +87,13 @@ This condition can be met using `#[used]` and `#[link_section]` plus a linker
 script.
 
 ``` rust,ignore
-#![feature(lang_items)]
+#![feature(panic_implementation)]
 #![feature(used)]
 #![no_main]
 #![no_std]
 
+use core::panic::PanicInfo;
+
 extern "C" fn reset_handler() -> ! {
     loop {}
 }
@@ -100,8 +102,10 @@ extern "C" fn reset_handler() -> ! {
 #[used]
 static RESET_HANDLER: extern "C" fn() -> ! = reset_handler;
 
-#[lang = "panic_fmt"]
-fn panic_fmt() {}
+#[panic_implementation]
+fn panic_impl(info: &PanicInfo) -> ! {
+    loop {}
+}
 ```
 
 ``` text
diff --git a/src/libcore/lib.rs b/src/libcore/lib.rs
index 32cf31231c3..e6ab64a3312 100644
--- a/src/libcore/lib.rs
+++ b/src/libcore/lib.rs
@@ -41,7 +41,7 @@
 //!   dictate the panic message, the file at which panic was invoked, and the
 //!   line and column inside the file. It is up to consumers of this core
 //!   library to define this panic function; it is only required to never
-//!   return. This requires a `lang` attribute named `panic_fmt`.
+//!   return. This requires a `lang` attribute named `panic_impl`.
 //!
 //! * `rust_eh_personality` - is used by the failure mechanisms of the
 //!    compiler. This is often mapped to GCC's personality function, but crates
diff --git a/src/librustc/diagnostics.rs b/src/librustc/diagnostics.rs
index 2662e709991..61f05ca3473 100644
--- a/src/librustc/diagnostics.rs
+++ b/src/librustc/diagnostics.rs
@@ -637,8 +637,8 @@ Erroneous code example:
 ```compile_fail,E0152
 #![feature(lang_items)]
 
-#[lang = "panic_fmt"]
-struct Foo; // error: duplicate lang item found: `panic_fmt`
+#[lang = "panic_impl"]
+struct Foo; // error: duplicate lang item found: `panic_impl`
 ```
 
 Lang items are already implemented in the standard library. Unless you are
@@ -824,7 +824,7 @@ A list of available external lang items is available in
 #![feature(lang_items)]
 
 extern "C" {
-    #[lang = "panic_fmt"] // ok!
+    #[lang = "panic_impl"] // ok!
     fn cake();
 }
 ```