diff --git a/src/liballoc/boxed.rs b/src/liballoc/boxed.rs
index e85b7d2d496..4783b4339da 100644
--- a/src/liballoc/boxed.rs
+++ b/src/liballoc/boxed.rs
@@ -137,7 +137,7 @@ pub struct IntermediateBox<T: ?Sized> {
 
 impl<T> Place<T> for IntermediateBox<T> {
     fn pointer(&mut self) -> *mut T {
-        unsafe { ::core::mem::transmute(self.ptr) }
+        self.ptr as *mut T
     }
 }
 
diff --git a/src/librbml/lib.rs b/src/librbml/lib.rs
index 4f7bbe9e027..1c6cb06d54a 100644
--- a/src/librbml/lib.rs
+++ b/src/librbml/lib.rs
@@ -932,15 +932,6 @@ pub fn new(w: &'a mut Cursor<Vec<u8>>) -> Encoder<'a> {
             }
         }
 
-        /// FIXME(pcwalton): Workaround for badness in trans. DO NOT USE ME.
-        pub unsafe fn unsafe_clone(&self) -> Encoder<'a> {
-            Encoder {
-                writer: mem::transmute_copy(&self.writer),
-                size_positions: self.size_positions.clone(),
-                relax_limit: self.relax_limit,
-            }
-        }
-
         pub fn start_tag(&mut self, tag_id: usize) -> EncodeResult {
             debug!("Start tag {:?}", tag_id);
             assert!(tag_id >= NUM_IMPLICIT_TAGS);
diff --git a/src/librustc_llvm/lib.rs b/src/librustc_llvm/lib.rs
index aa3a991b8b6..fe84cffa8c6 100644
--- a/src/librustc_llvm/lib.rs
+++ b/src/librustc_llvm/lib.rs
@@ -60,7 +60,7 @@
 
 use std::ffi::CString;
 use std::cell::RefCell;
-use std::{slice, mem};
+use std::slice;
 use libc::{c_uint, c_ushort, uint64_t, c_int, size_t, c_char};
 use libc::{c_longlong, c_ulonglong, c_void};
 use debuginfo::{DIBuilderRef, DIDescriptor,
@@ -2307,7 +2307,7 @@ pub enum RustString_opaque {}
                                                      size: size_t) {
     let slice = slice::from_raw_parts(ptr as *const u8, size as usize);
 
-    let sr: RustStringRepr = mem::transmute(sr);
+    let sr = sr as RustStringRepr;
     (*sr).borrow_mut().push_all(slice);
 }
 
diff --git a/src/librustc_trans/trans/base.rs b/src/librustc_trans/trans/base.rs
index af4f8aff113..fa562dadde3 100644
--- a/src/librustc_trans/trans/base.rs
+++ b/src/librustc_trans/trans/base.rs
@@ -89,7 +89,6 @@
 use std::ffi::{CStr, CString};
 use std::cell::{Cell, RefCell};
 use std::collections::{HashMap, HashSet};
-use std::mem;
 use std::str;
 use std::{i8, i16, i32, i64};
 use syntax::abi::{Rust, RustCall, RustIntrinsic, PlatformIntrinsic, Abi};
@@ -2664,11 +2663,7 @@ impl Iterator for ValueIter {
     fn next(&mut self) -> Option<ValueRef> {
         let old = self.cur;
         if !old.is_null() {
-            self.cur = unsafe {
-                let step: unsafe extern "C" fn(ValueRef) -> ValueRef =
-                    mem::transmute_copy(&self.step);
-                step(old)
-            };
+            self.cur = unsafe { (self.step)(old) };
             Some(old)
         } else {
             None
diff --git a/src/libstd/dynamic_lib.rs b/src/libstd/dynamic_lib.rs
index 7801662ff25..5629cba1e0b 100644
--- a/src/libstd/dynamic_lib.rs
+++ b/src/libstd/dynamic_lib.rs
@@ -22,7 +22,6 @@
 
 use env;
 use ffi::{CString, OsString};
-use mem;
 use path::{Path, PathBuf};
 
 pub struct DynamicLibrary {
@@ -114,7 +113,7 @@ pub unsafe fn symbol<T>(&self, symbol: &str) -> Result<*mut T, String> {
         // the destructor does not run.
         match maybe_symbol_value {
             Err(err) => Err(err),
-            Ok(symbol_value) => Ok(mem::transmute(symbol_value))
+            Ok(symbol_value) => Ok(symbol_value as *mut T)
         }
     }
 }