diff --git a/mk/platform.mk b/mk/platform.mk
index d1ec7c6500d25..dc2fe5c476db3 100644
--- a/mk/platform.mk
+++ b/mk/platform.mk
@@ -521,7 +521,7 @@ CFG_PATH_MUNGE_i686-w64-mingw32 :=
 CFG_LDPATH_i686-w64-mingw32 :=$(CFG_LDPATH_i686-w64-mingw32):$(PATH)
 CFG_RUN_i686-w64-mingw32=PATH="$(CFG_LDPATH_i686-w64-mingw32):$(1)" $(2)
 CFG_RUN_TARG_i686-w64-mingw32=$(call CFG_RUN_i686-w64-mingw32,$(HLIB$(1)_H_$(CFG_BUILD)),$(2))
-RUSTC_CROSS_FLAGS_i686-w64-mingw32 :=
+RUSTC_CROSS_FLAGS_i686-w64-mingw32 :=--cfg sjlj
 
 # x86_64-w64-mingw32 configuration
 CROSS_PREFIX_x86_64-w64-mingw32=x86_64-w64-mingw32-
diff --git a/src/librustrt/libunwind.rs b/src/librustrt/libunwind.rs
index f018b3fc16b3b..6f086026e4d11 100644
--- a/src/librustrt/libunwind.rs
+++ b/src/librustrt/libunwind.rs
@@ -98,10 +98,11 @@ extern {}
 extern "C" {
     // iOS on armv7 uses SjLj exceptions and requires to link
     // against corresponding routine (..._SjLj_...)
-    #[cfg(not(target_os = "ios", target_arch = "arm"))]
+    #[cfg(not(target_os = "ios", target_arch = "arm"), not(sjlj))]
     pub fn _Unwind_RaiseException(exception: *mut _Unwind_Exception)
                                   -> _Unwind_Reason_Code;
 
+    #[cfg(sjlj)]
     #[cfg(target_os = "ios", target_arch = "arm")]
     fn _Unwind_SjLj_RaiseException(e: *mut _Unwind_Exception)
                                    -> _Unwind_Reason_Code;
@@ -112,6 +113,7 @@ extern "C" {
 // ... and now we just providing access to SjLj counterspart
 // through a standard name to hide those details from others
 // (see also comment above regarding _Unwind_RaiseException)
+#[cfg(sjlj)]
 #[cfg(target_os = "ios", target_arch = "arm")]
 #[inline(always)]
 pub unsafe fn _Unwind_RaiseException(exc: *mut _Unwind_Exception)
diff --git a/src/librustrt/unwind.rs b/src/librustrt/unwind.rs
index f26cccdd3ed90..086f548da56cd 100644
--- a/src/librustrt/unwind.rs
+++ b/src/librustrt/unwind.rs
@@ -224,7 +224,7 @@ fn rust_exception_class() -> uw::_Unwind_Exception_Class {
 //   This is achieved by overriding the return value in search phase to always
 //   say "catch!".
 
-#[cfg(not(target_arch = "arm"), not(test))]
+#[cfg(not(target_arch = "arm"), not(test), not(sjlj))]
 #[doc(hidden)]
 #[allow(visible_private_types)]
 pub mod eabi {
@@ -279,6 +279,7 @@ pub mod eabi {
 // iOS on armv7 is using SjLj exceptions and therefore requires to use
 // a specialized personality routine: __gcc_personality_sj0
 
+#[cfg(sjlj)]
 #[cfg(target_os = "ios", target_arch = "arm", not(test))]
 #[doc(hidden)]
 #[allow(visible_private_types)]
@@ -521,3 +522,11 @@ pub unsafe fn register(f: Callback) -> bool {
         }
     }
 }
+
+// dummy functions for #12859
+#[cfg(sjlj)]
+#[no_mangle]
+#[allow(non_snake_case_functions)]
+pub extern "C" fn _Unwind_Resume(_ex_obj: *mut ()) {
+    // _ex_obj is actually *mut uw::_Unwind_Exception, but it is private
+}