diff --git a/tests/mir-opt/dataflow-const-prop/enum.constant.DataflowConstProp.diff b/tests/mir-opt/dataflow-const-prop/enum.constant.DataflowConstProp.32bit.diff
similarity index 100%
rename from tests/mir-opt/dataflow-const-prop/enum.constant.DataflowConstProp.diff
rename to tests/mir-opt/dataflow-const-prop/enum.constant.DataflowConstProp.32bit.diff
diff --git a/tests/mir-opt/dataflow-const-prop/enum.constant.DataflowConstProp.64bit.diff b/tests/mir-opt/dataflow-const-prop/enum.constant.DataflowConstProp.64bit.diff
new file mode 100644
index 00000000000..07ac5b72e24
--- /dev/null
+++ b/tests/mir-opt/dataflow-const-prop/enum.constant.DataflowConstProp.64bit.diff
@@ -0,0 +1,63 @@
+- // MIR for `constant` before DataflowConstProp
++ // MIR for `constant` after DataflowConstProp
+  
+  fn constant() -> () {
+      let mut _0: ();
+      let _1: E;
+      let mut _3: isize;
+      scope 1 {
+          debug e => _1;
+          let _2: i32;
+          let _4: i32;
+          let _5: i32;
+          scope 2 {
+              debug x => _2;
+          }
+          scope 3 {
+              debug x => _4;
+          }
+          scope 4 {
+              debug x => _5;
+          }
+      }
+  
+      bb0: {
+          StorageLive(_1);
+          _1 = const _;
+          StorageLive(_2);
+-         _3 = discriminant(_1);
+-         switchInt(move _3) -> [0: bb3, 1: bb1, otherwise: bb2];
++         _3 = const 0_isize;
++         switchInt(const 0_isize) -> [0: bb3, 1: bb1, otherwise: bb2];
+      }
+  
+      bb1: {
+          StorageLive(_5);
+          _5 = ((_1 as V2).0: i32);
+          _2 = _5;
+          StorageDead(_5);
+          goto -> bb4;
+      }
+  
+      bb2: {
+          unreachable;
+      }
+  
+      bb3: {
+          StorageLive(_4);
+-         _4 = ((_1 as V1).0: i32);
+-         _2 = _4;
++         _4 = const 0_i32;
++         _2 = const 0_i32;
+          StorageDead(_4);
+          goto -> bb4;
+      }
+  
+      bb4: {
+          _0 = const ();
+          StorageDead(_2);
+          StorageDead(_1);
+          return;
+      }
+  }
+  
diff --git a/tests/mir-opt/dataflow-const-prop/enum.multiple.DataflowConstProp.diff b/tests/mir-opt/dataflow-const-prop/enum.multiple.DataflowConstProp.32bit.diff
similarity index 100%
rename from tests/mir-opt/dataflow-const-prop/enum.multiple.DataflowConstProp.diff
rename to tests/mir-opt/dataflow-const-prop/enum.multiple.DataflowConstProp.32bit.diff
diff --git a/tests/mir-opt/dataflow-const-prop/enum.multiple.DataflowConstProp.64bit.diff b/tests/mir-opt/dataflow-const-prop/enum.multiple.DataflowConstProp.64bit.diff
new file mode 100644
index 00000000000..775325c4d06
--- /dev/null
+++ b/tests/mir-opt/dataflow-const-prop/enum.multiple.DataflowConstProp.64bit.diff
@@ -0,0 +1,82 @@
+- // MIR for `multiple` before DataflowConstProp
++ // MIR for `multiple` after DataflowConstProp
+  
+  fn multiple(_1: bool, _2: u8) -> () {
+      debug x => _1;
+      debug i => _2;
+      let mut _0: ();
+      let _3: std::option::Option<u8>;
+      let mut _4: bool;
+      let mut _5: u8;
+      let mut _7: isize;
+      scope 1 {
+          debug e => _3;
+          let _6: u8;
+          let _8: u8;
+          scope 2 {
+              debug x => _6;
+              let _9: u8;
+              scope 4 {
+                  debug y => _9;
+              }
+          }
+          scope 3 {
+              debug i => _8;
+          }
+      }
+  
+      bb0: {
+          StorageLive(_3);
+          StorageLive(_4);
+          _4 = _1;
+          switchInt(move _4) -> [0: bb2, otherwise: bb1];
+      }
+  
+      bb1: {
+          StorageLive(_5);
+          _5 = _2;
+          _3 = Option::<u8>::Some(move _5);
+          StorageDead(_5);
+          goto -> bb3;
+      }
+  
+      bb2: {
+          _3 = Option::<u8>::None;
+          goto -> bb3;
+      }
+  
+      bb3: {
+          StorageDead(_4);
+          StorageLive(_6);
+          _7 = discriminant(_3);
+          switchInt(move _7) -> [0: bb4, 1: bb6, otherwise: bb5];
+      }
+  
+      bb4: {
+          _6 = const 0_u8;
+          goto -> bb7;
+      }
+  
+      bb5: {
+          unreachable;
+      }
+  
+      bb6: {
+          StorageLive(_8);
+          _8 = ((_3 as Some).0: u8);
+          _6 = _8;
+          StorageDead(_8);
+          goto -> bb7;
+      }
+  
+      bb7: {
+          StorageLive(_9);
+          _9 = _6;
+          _0 = const ();
+          StorageDead(_9);
+          StorageDead(_6);
+          StorageDead(_3);
+          return;
+      }
+  }
+  
diff --git a/tests/mir-opt/dataflow-const-prop/enum.mutate_discriminant.DataflowConstProp.diff b/tests/mir-opt/dataflow-const-prop/enum.mutate_discriminant.DataflowConstProp.32bit.diff
similarity index 100%
rename from tests/mir-opt/dataflow-const-prop/enum.mutate_discriminant.DataflowConstProp.diff
rename to tests/mir-opt/dataflow-const-prop/enum.mutate_discriminant.DataflowConstProp.32bit.diff
diff --git a/tests/mir-opt/dataflow-const-prop/enum.mutate_discriminant.DataflowConstProp.64bit.diff b/tests/mir-opt/dataflow-const-prop/enum.mutate_discriminant.DataflowConstProp.64bit.diff
new file mode 100644
index 00000000000..960e69ee916
--- /dev/null
+++ b/tests/mir-opt/dataflow-const-prop/enum.mutate_discriminant.DataflowConstProp.64bit.diff
@@ -0,0 +1,26 @@
+- // MIR for `mutate_discriminant` before DataflowConstProp
++ // MIR for `mutate_discriminant` after DataflowConstProp
+  
+  fn mutate_discriminant() -> u8 {
+      let mut _0: u8;
+      let mut _1: std::option::Option<NonZeroUsize>;
+      let mut _2: isize;
+  
+      bb0: {
+          discriminant(_1) = 1;
+          (((_1 as variant#1).0: NonZeroUsize).0: usize) = const 0_usize;
+          _2 = discriminant(_1);
+          switchInt(_2) -> [0: bb1, otherwise: bb2];
+      }
+  
+      bb1: {
+          _0 = const 1_u8;
+          return;
+      }
+  
+      bb2: {
+          _0 = const 2_u8;
+          unreachable;
+      }
+  }
+  
diff --git a/tests/mir-opt/dataflow-const-prop/enum.rs b/tests/mir-opt/dataflow-const-prop/enum.rs
index 6b745707592..5a10e9e883d 100644
--- a/tests/mir-opt/dataflow-const-prop/enum.rs
+++ b/tests/mir-opt/dataflow-const-prop/enum.rs
@@ -1,4 +1,5 @@
 // unit-test: DataflowConstProp
+// EMIT_MIR_FOR_EACH_BIT_WIDTH
 
 #![feature(custom_mir, core_intrinsics, rustc_attrs)]
 
diff --git a/tests/mir-opt/dataflow-const-prop/enum.simple.DataflowConstProp.diff b/tests/mir-opt/dataflow-const-prop/enum.simple.DataflowConstProp.32bit.diff
similarity index 100%
rename from tests/mir-opt/dataflow-const-prop/enum.simple.DataflowConstProp.diff
rename to tests/mir-opt/dataflow-const-prop/enum.simple.DataflowConstProp.32bit.diff
diff --git a/tests/mir-opt/dataflow-const-prop/enum.simple.DataflowConstProp.64bit.diff b/tests/mir-opt/dataflow-const-prop/enum.simple.DataflowConstProp.64bit.diff
new file mode 100644
index 00000000000..3946e7c7d96
--- /dev/null
+++ b/tests/mir-opt/dataflow-const-prop/enum.simple.DataflowConstProp.64bit.diff
@@ -0,0 +1,63 @@
+- // MIR for `simple` before DataflowConstProp
++ // MIR for `simple` after DataflowConstProp
+  
+  fn simple() -> () {
+      let mut _0: ();
+      let _1: E;
+      let mut _3: isize;
+      scope 1 {
+          debug e => _1;
+          let _2: i32;
+          let _4: i32;
+          let _5: i32;
+          scope 2 {
+              debug x => _2;
+          }
+          scope 3 {
+              debug x => _4;
+          }
+          scope 4 {
+              debug x => _5;
+          }
+      }
+  
+      bb0: {
+          StorageLive(_1);
+          _1 = E::V1(const 0_i32);
+          StorageLive(_2);
+-         _3 = discriminant(_1);
+-         switchInt(move _3) -> [0: bb3, 1: bb1, otherwise: bb2];
++         _3 = const 0_isize;
++         switchInt(const 0_isize) -> [0: bb3, 1: bb1, otherwise: bb2];
+      }
+  
+      bb1: {
+          StorageLive(_5);
+          _5 = ((_1 as V2).0: i32);
+          _2 = _5;
+          StorageDead(_5);
+          goto -> bb4;
+      }
+  
+      bb2: {
+          unreachable;
+      }
+  
+      bb3: {
+          StorageLive(_4);
+-         _4 = ((_1 as V1).0: i32);
+-         _2 = _4;
++         _4 = const 0_i32;
++         _2 = const 0_i32;
+          StorageDead(_4);
+          goto -> bb4;
+      }
+  
+      bb4: {
+          _0 = const ();
+          StorageDead(_2);
+          StorageDead(_1);
+          return;
+      }
+  }
+  
diff --git a/tests/mir-opt/dataflow-const-prop/enum.statics.DataflowConstProp.32bit.diff b/tests/mir-opt/dataflow-const-prop/enum.statics.DataflowConstProp.32bit.diff
new file mode 100644
index 00000000000..ae8b44c953e
--- /dev/null
+++ b/tests/mir-opt/dataflow-const-prop/enum.statics.DataflowConstProp.32bit.diff
@@ -0,0 +1,126 @@
+- // MIR for `statics` before DataflowConstProp
++ // MIR for `statics` after DataflowConstProp
+  
+  fn statics() -> () {
+      let mut _0: ();
+      let _1: E;
+      let mut _2: &E;
+      let mut _4: isize;
+      let mut _8: &&E;
+      let mut _10: isize;
+      scope 1 {
+          debug e => _1;
+          let _3: i32;
+          let _5: i32;
+          let _6: i32;
+          scope 2 {
+              debug x => _3;
+              let _7: &E;
+              scope 5 {
+                  debug e => _7;
+                  let _9: &i32;
+                  let _11: &i32;
+                  let _12: &i32;
+                  scope 6 {
+                      debug x => _9;
+                  }
+                  scope 7 {
+                      debug x => _11;
+                  }
+                  scope 8 {
+                      debug x => _12;
+                  }
+              }
+          }
+          scope 3 {
+              debug x => _5;
+          }
+          scope 4 {
+              debug x => _6;
+          }
+      }
+  
+      bb0: {
+          StorageLive(_1);
+          StorageLive(_2);
+          _2 = const {alloc1: &E};
+          _1 = (*_2);
+          StorageDead(_2);
+          StorageLive(_3);
+-         _4 = discriminant(_1);
+-         switchInt(move _4) -> [0: bb3, 1: bb1, otherwise: bb2];
++         _4 = const 0_isize;
++         switchInt(const 0_isize) -> [0: bb3, 1: bb1, otherwise: bb2];
+      }
+  
+      bb1: {
+          StorageLive(_6);
+          _6 = ((_1 as V2).0: i32);
+          _3 = _6;
+          StorageDead(_6);
+          goto -> bb4;
+      }
+  
+      bb2: {
+          unreachable;
+      }
+  
+      bb3: {
+          StorageLive(_5);
+-         _5 = ((_1 as V1).0: i32);
+-         _3 = _5;
++         _5 = const 0_i32;
++         _3 = const 0_i32;
+          StorageDead(_5);
+          goto -> bb4;
+      }
+  
+      bb4: {
+          StorageLive(_7);
+          StorageLive(_8);
+          _8 = const {alloc2: &&E};
+          _7 = (*_8);
+          StorageDead(_8);
+          StorageLive(_9);
+          _10 = discriminant((*_7));
+          switchInt(move _10) -> [0: bb6, 1: bb5, otherwise: bb2];
+      }
+  
+      bb5: {
+          StorageLive(_12);
+          _12 = &(((*_7) as V2).0: i32);
+          _9 = &(*_12);
+          StorageDead(_12);
+          goto -> bb7;
+      }
+  
+      bb6: {
+          StorageLive(_11);
+          _11 = &(((*_7) as V1).0: i32);
+          _9 = _11;
+          StorageDead(_11);
+          goto -> bb7;
+      }
+  
+      bb7: {
+          _0 = const ();
+          StorageDead(_9);
+          StorageDead(_7);
+          StorageDead(_3);
+          StorageDead(_1);
+          return;
+      }
+  }
+  
+  alloc2 (static: RC, size: 4, align: 4) {
+      ╾─alloc14─╼                                     │ ╾──╼
+  }
+  
+  alloc14 (size: 8, align: 4) {
+      01 00 00 00 04 00 00 00                         │ ........
+  }
+  
+  alloc1 (static: statics::C, size: 8, align: 4) {
+      00 00 00 00 00 00 00 00                         │ ........
+  }
+  
diff --git a/tests/mir-opt/dataflow-const-prop/enum.statics.DataflowConstProp.diff b/tests/mir-opt/dataflow-const-prop/enum.statics.DataflowConstProp.64bit.diff
similarity index 100%
rename from tests/mir-opt/dataflow-const-prop/enum.statics.DataflowConstProp.diff
rename to tests/mir-opt/dataflow-const-prop/enum.statics.DataflowConstProp.64bit.diff
diff --git a/tests/mir-opt/dataflow-const-prop/struct.main.DataflowConstProp.32bit.diff b/tests/mir-opt/dataflow-const-prop/struct.main.DataflowConstProp.32bit.diff
new file mode 100644
index 00000000000..2de6ba307d5
--- /dev/null
+++ b/tests/mir-opt/dataflow-const-prop/struct.main.DataflowConstProp.32bit.diff
@@ -0,0 +1,129 @@
+- // MIR for `main` before DataflowConstProp
++ // MIR for `main` after DataflowConstProp
+  
+  fn main() -> () {
+      let mut _0: ();
+      let mut _1: S;
+      let mut _3: i32;
+      let mut _5: i32;
+      let mut _6: i32;
+      let mut _11: BigStruct;
+      let mut _16: &&BigStruct;
+      let mut _17: &BigStruct;
+      let mut _18: &BigStruct;
+      let mut _19: &BigStruct;
+      let mut _20: &BigStruct;
+      let mut _21: &BigStruct;
+      scope 1 {
+          debug s => _1;
+          let _2: i32;
+          scope 2 {
+              debug a => _2;
+              let _4: i32;
+              scope 3 {
+                  debug b => _4;
+                  let _7: S;
+                  let _8: u8;
+                  let _9: f32;
+                  let _10: S;
+                  scope 4 {
+                      debug a => _7;
+                      debug b => _8;
+                      debug c => _9;
+                      debug d => _10;
+                      let _12: S;
+                      let _13: u8;
+                      let _14: f32;
+                      let _15: S;
+                      scope 5 {
+                          debug a => _12;
+                          debug b => _13;
+                          debug c => _14;
+                          debug d => _15;
+                      }
+                  }
+              }
+          }
+      }
+  
+      bb0: {
+          StorageLive(_1);
+          _1 = S(const 1_i32);
+          StorageLive(_2);
+          StorageLive(_3);
+-         _3 = (_1.0: i32);
+-         _2 = Add(move _3, const 2_i32);
++         _3 = const 1_i32;
++         _2 = const 3_i32;
+          StorageDead(_3);
+          (_1.0: i32) = const 3_i32;
+          StorageLive(_4);
+          StorageLive(_5);
+-         _5 = _2;
++         _5 = const 3_i32;
+          StorageLive(_6);
+-         _6 = (_1.0: i32);
+-         _4 = Add(move _5, move _6);
++         _6 = const 3_i32;
++         _4 = const 6_i32;
+          StorageDead(_6);
+          StorageDead(_5);
+          StorageLive(_11);
+          _11 = const _;
+          StorageLive(_7);
+-         _7 = (_11.0: S);
++         _7 = const S(1_i32);
+          StorageLive(_8);
+-         _8 = (_11.1: u8);
++         _8 = const 5_u8;
+          StorageLive(_9);
+-         _9 = (_11.2: f32);
++         _9 = const 7f32;
+          StorageLive(_10);
+-         _10 = (_11.3: S);
++         _10 = const S(13_i32);
+          StorageDead(_11);
+          StorageLive(_16);
+          _16 = const {alloc1: &&BigStruct};
+          _17 = deref_copy (*_16);
+          StorageLive(_12);
+          _18 = deref_copy (*_16);
+-         _12 = ((*_18).0: S);
++         _12 = const S(1_i32);
+          StorageLive(_13);
+          _19 = deref_copy (*_16);
+-         _13 = ((*_19).1: u8);
++         _13 = const 5_u8;
+          StorageLive(_14);
+          _20 = deref_copy (*_16);
+-         _14 = ((*_20).2: f32);
++         _14 = const 7f32;
+          StorageLive(_15);
+          _21 = deref_copy (*_16);
+-         _15 = ((*_21).3: S);
++         _15 = const S(13_i32);
+          StorageDead(_16);
+          _0 = const ();
+          StorageDead(_15);
+          StorageDead(_14);
+          StorageDead(_13);
+          StorageDead(_12);
+          StorageDead(_10);
+          StorageDead(_9);
+          StorageDead(_8);
+          StorageDead(_7);
+          StorageDead(_4);
+          StorageDead(_2);
+          StorageDead(_1);
+          return;
+      }
+  }
+  
+  alloc1 (static: STAT, size: 4, align: 4) {
+      ╾─alloc15─╼                                     │ ╾──╼
+  }
+  
+  alloc15 (size: 16, align: 4) {
+      01 00 00 00 00 00 e0 40 0d 00 00 00 05 __ __ __ │ .......@.....░░░
+  }
+  
diff --git a/tests/mir-opt/dataflow-const-prop/struct.main.DataflowConstProp.diff b/tests/mir-opt/dataflow-const-prop/struct.main.DataflowConstProp.64bit.diff
similarity index 100%
rename from tests/mir-opt/dataflow-const-prop/struct.main.DataflowConstProp.diff
rename to tests/mir-opt/dataflow-const-prop/struct.main.DataflowConstProp.64bit.diff
diff --git a/tests/mir-opt/dataflow-const-prop/struct.rs b/tests/mir-opt/dataflow-const-prop/struct.rs
index c171ed74c54..e92a1676d3f 100644
--- a/tests/mir-opt/dataflow-const-prop/struct.rs
+++ b/tests/mir-opt/dataflow-const-prop/struct.rs
@@ -1,4 +1,5 @@
 // unit-test: DataflowConstProp
+// EMIT_MIR_FOR_EACH_BIT_WIDTH
 
 #[derive(Copy, Clone)]
 struct S(i32);