diff --git a/compiler/rustc_mir_transform/src/simplify_branches.rs b/compiler/rustc_mir_transform/src/simplify_branches.rs
index 8164b3052786a..eb24fd6b4c896 100644
--- a/compiler/rustc_mir_transform/src/simplify_branches.rs
+++ b/compiler/rustc_mir_transform/src/simplify_branches.rs
@@ -1,3 +1,4 @@
+use crate::dataflow_const_prop::DataflowConstProp;
 use crate::MirPass;
 use rustc_middle::mir::*;
 use rustc_middle::ty::TyCtxt;
@@ -19,29 +20,42 @@ impl<'tcx> MirPass<'tcx> for SimplifyConstCondition {
     }
 
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
-        let param_env = tcx.param_env(body.source.def_id());
-        for block in body.basic_blocks_mut() {
-            let terminator = block.terminator_mut();
-            terminator.kind = match terminator.kind {
-                TerminatorKind::SwitchInt {
-                    discr: Operand::Constant(ref c), ref targets, ..
-                } => {
-                    let constant = c.literal.try_eval_bits(tcx, param_env, c.ty());
-                    if let Some(constant) = constant {
-                        let target = targets.target_for_value(constant);
-                        TerminatorKind::Goto { target }
-                    } else {
-                        continue;
+        loop {
+            let mut changed = false;
+            let param_env = tcx.param_env(body.source.def_id());
+            for block in body.basic_blocks_mut() {
+                let terminator = block.terminator_mut();
+                terminator.kind = match terminator.kind {
+                    TerminatorKind::SwitchInt {
+                        discr: Operand::Constant(ref c),
+                        ref targets,
+                        ..
+                    } => {
+                        let constant = c.literal.try_eval_bits(tcx, param_env, c.ty());
+                        if let Some(constant) = constant {
+                            changed = true;
+                            let target = targets.target_for_value(constant);
+                            TerminatorKind::Goto { target }
+                        } else {
+                            continue;
+                        }
                     }
-                }
-                TerminatorKind::Assert {
-                    target, cond: Operand::Constant(ref c), expected, ..
-                } => match c.literal.try_eval_bool(tcx, param_env) {
-                    Some(v) if v == expected => TerminatorKind::Goto { target },
+                    TerminatorKind::Assert {
+                        target,
+                        cond: Operand::Constant(ref c),
+                        expected,
+                        ..
+                    } => match c.literal.try_eval_bool(tcx, param_env) {
+                        Some(v) if v == expected => {
+                            changed = true;
+                            TerminatorKind::Goto { target }
+                        }
+                        _ => continue,
+                    },
                     _ => continue,
-                },
-                _ => continue,
-            };
+                };
+            }
+            if !changed { break } else { DataflowConstProp.run_pass(tcx, body) }
         }
     }
 }