diff --git a/src/rt/rust_upcall.cpp b/src/rt/rust_upcall.cpp
index 7ccb06a3296..e7648a081be 100644
--- a/src/rt/rust_upcall.cpp
+++ b/src/rt/rust_upcall.cpp
@@ -26,34 +26,6 @@ typedef int _Unwind_Action;
 struct _Unwind_Context;
 struct _Unwind_Exception;
 
-typedef void (*CDECL stack_switch_shim)(void*);
-
-/**********************************************************************
- * Switches to the C-stack and invokes |fn_ptr|, passing |args| as argument.
- * This is used by the C compiler to call foreign functions and by other
- * upcalls to switch to the C stack.  The return value is passed through a
- * field in the args parameter. This upcall is specifically for switching
- * to the shim functions generated by rustc.
- */
-extern "C" CDECL void
-upcall_call_shim_on_c_stack(void *args, void *fn_ptr) {
-    stack_switch_shim f = (stack_switch_shim)fn_ptr;
-    f(args);
-}
-
-/*
- * The opposite of above. Starts on a C stack and switches to the Rust
- * stack. This is the only upcall that runs from the C stack.
- */
-extern "C" CDECL void
-upcall_call_shim_on_rust_stack(void *args, void *fn_ptr) {
-    // There's no task. Call the function and hope for the best
-    stack_switch_shim f = (stack_switch_shim)fn_ptr;
-    f(args);
-}
-
-/**********************************************************************/
-
 #ifdef __SEH__
 #  define PERSONALITY_FUNC __gxx_personality_seh0
 #else
@@ -107,19 +79,6 @@ upcall_rust_personality(int version,
     return args.retval;
 }
 
-// NB: This needs to be blazing fast. Don't switch stacks
-extern "C" CDECL void *
-upcall_new_stack(size_t stk_sz, void *args_addr, size_t args_sz) {
-    assert(false && "newsched shouldn't be growing the stack");
-    return NULL;
-}
-
-// NB: This needs to be blazing fast. Don't switch stacks
-extern "C" CDECL void
-upcall_del_stack() {
-    assert(false && "newsched shouldn't be growing the stack");
-}
-
 // Landing pads need to call this to insert the
 // correct limit into TLS.
 // NB: This must run on the Rust stack because it
diff --git a/src/rt/rustrt.def.in b/src/rt/rustrt.def.in
index 47c9554daa0..60e4d3abd7a 100644
--- a/src/rt/rustrt.def.in
+++ b/src/rt/rustrt.def.in
@@ -25,10 +25,6 @@ rust_win32_rand_acquire
 rust_win32_rand_gen
 rust_win32_rand_release
 upcall_rust_personality
-upcall_call_shim_on_c_stack
-upcall_call_shim_on_rust_stack
-upcall_new_stack
-upcall_del_stack
 upcall_reset_stack_limit
 rust_uv_loop_new
 rust_uv_loop_delete