diff --git a/src/abi/mod.rs b/src/abi/mod.rs
index 416ed3ebe49a..329bdea79e8d 100644
--- a/src/abi/mod.rs
+++ b/src/abi/mod.rs
@@ -353,7 +353,7 @@ pub fn codegen_fn_prelude(fx: &mut FunctionCx<'_, '_, impl Backend>, start_ebb:
             ArgKind::Normal(Some(val)) => {
                 if let Some(addr) = val.try_to_addr() {
                     let local_decl = &fx.mir.local_decls[local];
-                    //                             v this ! is important
+                    //                       v this ! is important
                     let internally_mutable = !val.layout().ty.is_freeze(
                         fx.tcx,
                         ParamEnv::reveal_all(),
@@ -398,7 +398,7 @@ pub fn codegen_fn_prelude(fx: &mut FunctionCx<'_, '_, impl Backend>, start_ebb:
     }
 
     for local in fx.mir.vars_and_temps_iter() {
-        let ty = fx.mir.local_decls[local].ty;
+        let ty = fx.monomorphize(&fx.mir.local_decls[local].ty);
         let layout = fx.layout_of(ty);
 
         let is_ssa = *ssa_analyzed.get(&local).unwrap() == crate::analyze::SsaKind::Ssa;
diff --git a/src/base.rs b/src/base.rs
index 16a90becd621..00e5d965d943 100644
--- a/src/base.rs
+++ b/src/base.rs
@@ -340,29 +340,27 @@ fn trans_stmt<'tcx>(
                     };
                     lval.write_cvalue(fx, res);
                 }
-                Rvalue::Cast(CastKind::Pointer(PointerCast::ReifyFnPointer), operand, ty) => {
-                    let layout = fx.layout_of(ty);
-                    match fx
-                        .monomorphize(&operand.ty(&fx.mir.local_decls, fx.tcx))
-                        .kind
-                    {
+                Rvalue::Cast(CastKind::Pointer(PointerCast::ReifyFnPointer), operand, to_ty) => {
+                    let from_ty = fx.monomorphize(&operand.ty(&fx.mir.local_decls, fx.tcx));
+                    let to_layout = fx.layout_of(fx.monomorphize(to_ty));
+                    match from_ty.kind {
                         ty::FnDef(def_id, substs) => {
                             let func_ref = fx.get_function_ref(
                                 Instance::resolve(fx.tcx, ParamEnv::reveal_all(), def_id, substs)
                                     .unwrap(),
                             );
                             let func_addr = fx.bcx.ins().func_addr(fx.pointer_type, func_ref);
-                            lval.write_cvalue(fx, CValue::by_val(func_addr, layout));
+                            lval.write_cvalue(fx, CValue::by_val(func_addr, to_layout));
                         }
-                        _ => bug!("Trying to ReifyFnPointer on non FnDef {:?}", ty),
+                        _ => bug!("Trying to ReifyFnPointer on non FnDef {:?}", from_ty),
                     }
                 }
-                Rvalue::Cast(CastKind::Pointer(PointerCast::UnsafeFnPointer), operand, ty)
-                | Rvalue::Cast(CastKind::Pointer(PointerCast::MutToConstPointer), operand, ty)
-                | Rvalue::Cast(CastKind::Pointer(PointerCast::ArrayToPointer), operand, ty) => {
+                Rvalue::Cast(CastKind::Pointer(PointerCast::UnsafeFnPointer), operand, to_ty)
+                | Rvalue::Cast(CastKind::Pointer(PointerCast::MutToConstPointer), operand, to_ty)
+                | Rvalue::Cast(CastKind::Pointer(PointerCast::ArrayToPointer), operand, to_ty) => {
+                    let to_layout = fx.layout_of(fx.monomorphize(to_ty));
                     let operand = trans_operand(fx, operand);
-                    let layout = fx.layout_of(ty);
-                    lval.write_cvalue(fx, operand.unchecked_cast_to(layout));
+                    lval.write_cvalue(fx, operand.unchecked_cast_to(to_layout));
                 }
                 Rvalue::Cast(CastKind::Misc, operand, to_ty) => {
                     let operand = trans_operand(fx, operand);
@@ -420,7 +418,7 @@ fn trans_stmt<'tcx>(
                         lval.write_cvalue(fx, CValue::by_val(res, dest_layout));
                     }
                 }
-                Rvalue::Cast(CastKind::Pointer(PointerCast::ClosureFnPointer(_)), operand, _ty) => {
+                Rvalue::Cast(CastKind::Pointer(PointerCast::ClosureFnPointer(_)), operand, _to_ty) => {
                     let operand = trans_operand(fx, operand);
                     match operand.layout().ty.kind {
                         ty::Closure(def_id, substs) => {
@@ -437,7 +435,7 @@ fn trans_stmt<'tcx>(
                         _ => bug!("{} cannot be cast to a fn ptr", operand.layout().ty),
                     }
                 }
-                Rvalue::Cast(CastKind::Pointer(PointerCast::Unsize), operand, _ty) => {
+                Rvalue::Cast(CastKind::Pointer(PointerCast::Unsize), operand, _to_ty) => {
                     let operand = trans_operand(fx, operand);
                     operand.unsize_value(fx, lval);
                 }
@@ -466,6 +464,7 @@ fn trans_stmt<'tcx>(
                     use rustc::middle::lang_items::ExchangeMallocFnLangItem;
 
                     let usize_type = fx.clif_type(fx.tcx.types.usize).unwrap();
+                    let content_ty = fx.monomorphize(content_ty);
                     let layout = fx.layout_of(content_ty);
                     let llsize = fx.bcx.ins().iconst(usize_type, layout.size.bytes() as i64);
                     let llalign = fx
@@ -494,7 +493,7 @@ fn trans_stmt<'tcx>(
                         .layout()
                         .ty
                         .is_sized(fx.tcx.at(DUMMY_SP), ParamEnv::reveal_all()));
-                    let ty_size = fx.layout_of(ty).size.bytes();
+                    let ty_size = fx.layout_of(fx.monomorphize(ty)).size.bytes();
                     let val = CValue::const_val(fx, fx.tcx.types.usize, ty_size.into());
                     lval.write_cvalue(fx, val);
                 }
diff --git a/src/common.rs b/src/common.rs
index 455bc99ff22b..c3a8b708ab6e 100644
--- a/src/common.rs
+++ b/src/common.rs
@@ -279,7 +279,7 @@ impl<'tcx, B: Backend> LayoutOf for FunctionCx<'_, 'tcx, B> {
     type TyLayout = TyLayout<'tcx>;
 
     fn layout_of(&self, ty: Ty<'tcx>) -> TyLayout<'tcx> {
-        let ty = self.monomorphize(&ty);
+        assert!(!ty.needs_subst());
         self.tcx
             .layout_of(ParamEnv::reveal_all().and(&ty))
             .unwrap_or_else(|e| {