diff --git a/compiler/forget/src/HIR/EnterSSA.ts b/compiler/forget/src/HIR/EnterSSA.ts
index 6cf31edec6..4d6c835620 100644
--- a/compiler/forget/src/HIR/EnterSSA.ts
+++ b/compiler/forget/src/HIR/EnterSSA.ts
@@ -121,6 +121,7 @@ class SSABuilder {
     const phi: Phi = {
       kind: "Phi",
       id: newId,
+      oldId,
       operands: predDefs,
     };
 
diff --git a/compiler/forget/src/HIR/HIR.ts b/compiler/forget/src/HIR/HIR.ts
index 4bb1c6c363..315de05ea6 100644
--- a/compiler/forget/src/HIR/HIR.ts
+++ b/compiler/forget/src/HIR/HIR.ts
@@ -193,6 +193,7 @@ export type InstructionValue =
 export type Phi = {
   kind: "Phi";
   id: Identifier;
+  oldId: Identifier;
   operands: Map<BasicBlock, Identifier>;
 };
 
diff --git a/compiler/forget/src/HIR/LeaveSSA.ts b/compiler/forget/src/HIR/LeaveSSA.ts
new file mode 100644
index 0000000000..ae1684483a
--- /dev/null
+++ b/compiler/forget/src/HIR/LeaveSSA.ts
@@ -0,0 +1,50 @@
+import { invariant } from "../CompilerError";
+import { HIRFunction, Identifier, Place } from "./HIR";
+import { eachInstructionOperand, eachTerminalOperand } from "./visitors";
+
+export default function leaveSSA(fn: HIRFunction) {
+  const ir = fn.body;
+  const entryBlock = ir.blocks.get(ir.entry);
+  invariant(entryBlock, "expected to find the entry basic block");
+  const originalIdMap = new Map<
+    /* SSA'd id */ Identifier,
+    /* original id*/ Identifier
+  >();
+
+  for (const [, block] of ir.blocks) {
+    for (const phi of block.phis) {
+      originalIdMap.set(phi.id, phi.oldId);
+      for (const [, ssaId] of phi.operands) {
+        originalIdMap.set(ssaId, phi.oldId);
+      }
+    }
+    block.phis.clear();
+  }
+
+  if (originalIdMap.size === 0) {
+    return;
+  }
+
+  function tryRewrite(place: Place) {
+    const originalId = originalIdMap.get(place.identifier);
+    if (originalId != null) {
+      place.identifier = originalId;
+    }
+  }
+
+  for (const [, block] of ir.blocks) {
+    for (const instr of block.instructions) {
+      // LValues also need to be rewritten as they might be declaring or reassigning an identifier
+      // that was previously SSA'd.
+      if (instr.lvalue != null) {
+        tryRewrite(instr.lvalue.place);
+      }
+      for (const place of eachInstructionOperand(instr)) {
+        tryRewrite(place);
+      }
+    }
+    for (const place of eachTerminalOperand(block.terminal)) {
+      tryRewrite(place);
+    }
+  }
+}
diff --git a/compiler/forget/src/__tests__/fixtures/hir/component.expect.md b/compiler/forget/src/__tests__/fixtures/hir/component.expect.md
index fb91041897..ce590067ce 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/component.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/component.expect.md
@@ -52,16 +52,15 @@ bb3:
   If (read $36) then:bb8 else:bb9
 bb8:
   predecessor blocks: bb3
-  [9] Const mutate $37 = read $36
+  [9] Const mutate $13 = read $36
   Goto bb7
 bb9:
   predecessor blocks: bb3
-  [10] Const mutate $39 = Call mutate seen$30.has(mutate item$10)
+  [10] Const mutate $13 = Call mutate seen$30.has(mutate item$10)
   Goto bb7
 bb7:
   predecessor blocks: bb8 bb9
-  $40: phi(bb8: $37, bb9: $39)
-  If (read $40) then:bb1 else:bb4
+  If (read $13) then:bb1 else:bb4
 bb4:
   predecessor blocks: bb7
   [11] Call mutate seen$30.add(mutate item$10)
diff --git a/compiler/forget/src/__tests__/fixtures/hir/hooks-freeze-possibly-mutable-arguments.expect.md b/compiler/forget/src/__tests__/fixtures/hir/hooks-freeze-possibly-mutable-arguments.expect.md
index cedbeacbf1..5a350ddf60 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/hooks-freeze-possibly-mutable-arguments.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/hooks-freeze-possibly-mutable-arguments.expect.md
@@ -32,19 +32,18 @@ bb0:
   If (read cond$8) then:bb2 else:bb3
 bb2:
   predecessor blocks: bb0
-  [4] Reassign mutate a$11 = read x$9
+  [4] Reassign mutate a$4 = read x$9
   Goto bb1
 bb3:
   predecessor blocks: bb0
-  [5] Reassign mutate a$12 = Array []
+  [5] Reassign mutate a$4 = Array []
   Goto bb1
 bb1:
   predecessor blocks: bb2 bb3
-  a$14: phi(bb2: a$11, bb3: a$12)
-  [6] Call read useFreeze$5(freeze a$14)
-  [7] Call read useFreeze$5(read a$14)
-  [8] Call mutate call$6(read a$14)
-  Return read a$14
+  [6] Call read useFreeze$5(freeze a$4)
+  [7] Call read useFreeze$5(read a$4)
+  [8] Call mutate call$6(read a$4)
+  Return read a$4
 ```
 
 ## Code
@@ -55,15 +54,15 @@ function Component$0(props$7) {
   const x$9 = props$7.x;
   let a$10 = undefined;
   bb1: if (cond$8) {
-    a$11 = x$9;
+    a$4 = x$9;
   } else {
-    a$12 = [];
+    a$4 = [];
   }
 
-  useFreeze$5(a$14);
-  useFreeze$5(a$14);
-  call$6(a$14);
-  return a$14;
+  useFreeze$5(a$4);
+  useFreeze$5(a$4);
+  call$6(a$4);
+  return a$4;
 }
 
 ```
diff --git a/compiler/forget/src/__tests__/fixtures/hir/logical-expression.expect.md b/compiler/forget/src/__tests__/fixtures/hir/logical-expression.expect.md
index 074ea39abd..21669b28f6 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/logical-expression.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/logical-expression.expect.md
@@ -27,16 +27,15 @@ bb0:
   If (read $5) then:bb2 else:bb3
 bb2:
   predecessor blocks: bb0
-  [2] Const mutate $6 = Call mutate g$4()
+  [2] Const mutate $3 = Call mutate g$4()
   Goto bb1
 bb3:
   predecessor blocks: bb0
-  [3] Const mutate $7 = read $5
+  [3] Const mutate $3 = read $5
   Goto bb1
 bb1:
   predecessor blocks: bb2 bb3
-  $8: phi(bb2: $6, bb3: $7)
-  Return freeze $8
+  Return freeze $3
 ```
 
 ## Code
@@ -46,7 +45,7 @@ function And$0() {
   bb1: if (f$1()) {
   } else {
   }
-  return t8;
+  return f$1();
 }
 
 ```
@@ -58,16 +57,15 @@ bb0:
   If (read $5) then:bb2 else:bb3
 bb2:
   predecessor blocks: bb0
-  [2] Const mutate $6 = read $5
+  [2] Const mutate $3 = read $5
   Goto bb1
 bb3:
   predecessor blocks: bb0
-  [3] Const mutate $7 = Call mutate g$4()
+  [3] Const mutate $3 = Call mutate g$4()
   Goto bb1
 bb1:
   predecessor blocks: bb2 bb3
-  $8: phi(bb2: $6, bb3: $7)
-  Return freeze $8
+  Return freeze $3
 ```
 
 ## Code
@@ -77,7 +75,7 @@ function Or$0() {
   bb1: if (f$1()) {
   } else {
   }
-  return t8;
+  return g$4();
 }
 
 ```
@@ -91,16 +89,15 @@ bb0:
   If (read $11) then:bb2 else:bb3
 bb2:
   predecessor blocks: bb0
-  [4] Const mutate $12 = read $9
+  [4] Const mutate $6 = read $9
   Goto bb1
 bb3:
   predecessor blocks: bb0
-  [5] Const mutate $13 = Call mutate g$7()
+  [5] Const mutate $6 = Call mutate g$7()
   Goto bb1
 bb1:
   predecessor blocks: bb2 bb3
-  $14: phi(bb2: $12, bb3: $13)
-  Return freeze $14
+  Return freeze $6
 ```
 
 ## Code
@@ -110,7 +107,7 @@ function QuestionQuestion$0(props$8) {
   bb1: if (f$2() != null) {
   } else {
   }
-  return t14;
+  return g$7();
 }
 
 ```
diff --git a/compiler/forget/src/__tests__/fixtures/hir/mutable-lifetime-loops.expect.md b/compiler/forget/src/__tests__/fixtures/hir/mutable-lifetime-loops.expect.md
index 3ebca18d96..8b0c352270 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/mutable-lifetime-loops.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/mutable-lifetime-loops.expect.md
@@ -73,49 +73,41 @@ function cond$0(x$2) {
 
 ```
 bb0:
-  [1] Let mutate a$13 = Object {  }
-  [2] Let mutate b$14 = Object {  }
-  [3] Let mutate c$15 = Object {  }
-  [4] Let mutate d$16 = Object {  }
+  [1] Let mutate a$2 = Object {  }
+  [2] Let mutate b$3 = Object {  }
+  [3] Let mutate c$4 = Object {  }
+  [4] Let mutate d$5 = Object {  }
   Goto bb1
 bb1:
   predecessor blocks: bb0 bb3
-  a$18: phi(bb0: a$13, bb3: a$21)
-  b$20: phi(bb0: b$14, bb3: b$23)
-  c$22: phi(bb0: c$15, bb3: c$25)
-  d$24: phi(bb0: d$16, bb3: d$26)
   [5] Const mutate $17 = true
   If (read $17) then:bb3 else:bb2
 bb3:
   predecessor blocks: bb1
-  [6] Let mutate z$19 = read a$18
-  [7] Reassign mutate a$21[7:12] = read b$20
-  [8] Reassign mutate b$23[8:11] = read c$22
-  [9] Reassign mutate c$25 = read d$24
-  [10] Reassign mutate d$26 = read z$19
-  [11] Call mutate mutate$7(mutate a$21, mutate b$23)
-  [12] Const mutate $29 = Call mutate cond$8(mutate a$21)
+  [6] Let mutate z$19 = read a$2
+  [7] Reassign mutate a$2 = read b$3
+  [8] Reassign mutate b$3 = read c$4
+  [9] Reassign mutate c$4 = read d$5
+  [10] Reassign mutate d$5 = read z$19
+  [11] Call mutate mutate$7(mutate a$2, mutate b$3)
+  [12] Const mutate $29 = Call mutate cond$8(mutate a$2)
   If (read $29) then:bb2 else:bb1
 bb2:
   predecessor blocks: bb3 bb1
-  a$30: phi(bb3: a$21, bb1: a$18)
-  b$31: phi(bb3: b$23, bb1: b$20)
-  c$32: phi(bb3: c$25, bb1: c$22)
-  d$33[-1:14]: phi(bb3: d$26, bb1: d$24)
-  If (read a$30) then:bb7 else:bb7
+  If (read a$2) then:bb7 else:bb7
 bb7:
   predecessor blocks: bb2
-  If (read b$31) then:bb9 else:bb9
+  If (read b$3) then:bb9 else:bb9
 bb9:
   predecessor blocks: bb7
-  If (read c$32) then:bb11 else:bb11
+  If (read c$4) then:bb11 else:bb11
 bb11:
   predecessor blocks: bb9
-  If (read d$33) then:bb13 else:bb13
+  If (read d$5) then:bb13 else:bb13
 bb13:
   predecessor blocks: bb11
   [13] Const mutate $34 = null
-  [14] Call mutate mutate$7(mutate d$33, read $34)
+  [14] Call mutate mutate$7(mutate d$5, read $34)
   Return
 ```
 
@@ -123,10 +115,10 @@ bb13:
 
 ```javascript
 function Component$0(props$12) {
-  let a$13 = {};
-  let b$14 = {};
-  let c$15 = {};
-  let d$16 = {};
+  let a$2 = {};
+  let b$3 = {};
+  let c$4 = {};
+  let d$5 = {};
 }
 
 ```
diff --git a/compiler/forget/src/__tests__/fixtures/hir/reassignment-conditional.expect.md b/compiler/forget/src/__tests__/fixtures/hir/reassignment-conditional.expect.md
index 527df2ecd4..7ae0a7c8ab 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/reassignment-conditional.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/reassignment-conditional.expect.md
@@ -23,20 +23,19 @@ function Component(props) {
 
 ```
 bb0:
-  [1] Let mutate x$7[1:2] = Array []
-  [2] Call mutate x$7.push(read props$6.p0)
-  [3] Let mutate y$8 = read x$7
+  [1] Let mutate x$2 = Array []
+  [2] Call mutate x$2.push(read props$6.p0)
+  [3] Let mutate y$8 = read x$2
   If (read props$6.p1) then:bb2 else:bb1
 bb2:
   predecessor blocks: bb0
-  [4] Reassign mutate x$9 = Array []
+  [4] Reassign mutate x$2 = Array []
   Goto bb1
 bb1:
   predecessor blocks: bb2 bb0
-  x$11: phi(bb2: x$9, bb0: x$7)
-  [5] Let mutate _$12 = JSX <read Component$0 x={freeze x$11} ></read Component$0>
+  [5] Let mutate _$12 = JSX <read Component$0 x={freeze x$2} ></read Component$0>
   [6] Call read y$8.push(read props$6.p2)
-  [7] Const mutate $15 = JSX <read Component$0 x={read x$11} y={read y$8} ></read Component$0>
+  [7] Const mutate $15 = JSX <read Component$0 x={read x$2} y={read y$8} ></read Component$0>
   Return read $15
 ```
 
@@ -44,17 +43,17 @@ bb1:
 
 ```javascript
 function Component$0(props$6) {
-  let x$7 = [];
-  x$7.push(props$6.p0);
-  let y$8 = x$7;
+  let x$2 = [];
+  x$2.push(props$6.p0);
+  let y$8 = x$2;
   bb1: if (props$6.p1) {
-    x$9 = [];
+    x$2 = [];
   }
 
-  let _$12 = <Component$0 x={x$11}></Component$0>;
+  let _$12 = <Component$0 x={x$2}></Component$0>;
 
   y$8.push(props$6.p2);
-  return <Component$0 x={x$11} y={y$8}></Component$0>;
+  return <Component$0 x={x$2} y={y$8}></Component$0>;
 }
 
 ```
diff --git a/compiler/forget/src/__tests__/fixtures/hir/reverse-postorder.expect.md b/compiler/forget/src/__tests__/fixtures/hir/reverse-postorder.expect.md
index 8ba7c8b9ce..79b996bb94 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/reverse-postorder.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/reverse-postorder.expect.md
@@ -50,31 +50,30 @@ bb2:
     Default: bb4
 bb8:
   predecessor blocks: bb2
-  [5] Reassign mutate x$11 = read props$6.v0
+  [5] Reassign mutate x$2 = read props$6.v0
   Goto bb1
 bb6:
   predecessor blocks: bb2
-  [6] Reassign mutate x$12 = read props$6.v1
+  [6] Reassign mutate x$2 = read props$6.v1
   Goto bb1
 bb4:
   predecessor blocks: bb2
-  [7] Reassign mutate x$13 = read props$6.v2
+  [7] Reassign mutate x$2 = read props$6.v2
   Goto bb1
 bb10:
   predecessor blocks: bb0
   If (read props$6.cond2) then:bb12 else:bb13
 bb12:
   predecessor blocks: bb10
-  [8] Reassign mutate x$14 = read props$6.b
+  [8] Reassign mutate x$2 = read props$6.b
   Goto bb1
 bb13:
   predecessor blocks: bb10
-  [9] Reassign mutate x$15 = read props$6.c
+  [9] Reassign mutate x$2 = read props$6.c
   Goto bb1
 bb1:
   predecessor blocks: bb8 bb6 bb4 bb12 bb13
-  x$16: phi(bb8: x$11, bb6: x$12, bb4: x$13, bb12: x$14, bb13: x$15)
-  [10] read x$16
+  [10] read x$2
   Return
 ```
 
@@ -86,12 +85,12 @@ function Component$0(props$6) {
   bb1: if (props$6.cond) {
     switch (props$6.test) {
       case 0: {
-        x$11 = props$6.v0;
+        x$2 = props$6.v0;
         break bb1;
       }
 
       case 1: {
-        x$12 = props$6.v1;
+        x$2 = props$6.v1;
         break bb1;
       }
 
@@ -99,18 +98,18 @@ function Component$0(props$6) {
       }
 
       default: {
-        x$13 = props$6.v2;
+        x$2 = props$6.v2;
       }
     }
   } else {
     if (props$6.cond2) {
-      x$14 = props$6.b;
+      x$2 = props$6.b;
     } else {
-      x$15 = props$6.c;
+      x$2 = props$6.c;
     }
   }
 
-  x$16;
+  x$2;
   return;
 }
 
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-complex-multiple-if.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-complex-multiple-if.expect.md
index 7e66da4401..a57cbf2203 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-complex-multiple-if.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-complex-multiple-if.expect.md
@@ -21,29 +21,27 @@ function foo() {
 
 ```
 bb0:
-  [1] Let mutate x$7 = 1
+  [1] Let mutate x$1 = 1
   [2] Let mutate y$8 = 2
   [3] Const mutate $9 = 2
   [4] Const mutate $10 = Binary read y$8 === read $9
   If (read $10) then:bb2 else:bb1
 bb2:
   predecessor blocks: bb0
-  [5] Reassign mutate x$11 = 3
+  [5] Reassign mutate x$1 = 3
   Goto bb1
 bb1:
   predecessor blocks: bb2 bb0
-  x$17: phi(bb2: x$11, bb0: x$7)
   [6] Const mutate $12 = 3
   [7] Const mutate $14 = Binary read y$8 === read $12
   If (read $14) then:bb4 else:bb3
 bb4:
   predecessor blocks: bb1
-  [8] Reassign mutate x$15 = 5
+  [8] Reassign mutate x$1 = 5
   Goto bb3
 bb3:
   predecessor blocks: bb4 bb1
-  x$16: phi(bb4: x$15, bb1: x$17)
-  [9] Reassign mutate y$18 = read x$16
+  [9] Reassign mutate y$18 = read x$1
   Return
 ```
 
@@ -51,17 +49,17 @@ bb3:
 
 ```javascript
 function foo$0() {
-  let x$7 = 1;
+  let x$1 = 1;
   let y$8 = 2;
   bb1: if (y$8 === 2) {
-    x$11 = 3;
+    x$1 = 3;
   }
 
   bb3: if (y$8 === 3) {
-    x$15 = 5;
+    x$1 = 5;
   }
 
-  y$18 = x$16;
+  y$18 = x$1;
   return;
 }
 
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-complex-single-if.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-complex-single-if.expect.md
index ad136317dd..79dedcc9c2 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-complex-single-if.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-complex-single-if.expect.md
@@ -18,19 +18,18 @@ function foo() {
 
 ```
 bb0:
-  [1] Let mutate x$5 = 1
+  [1] Let mutate x$1 = 1
   [2] Let mutate y$6 = 2
   [3] Const mutate $7 = 2
   [4] Const mutate $8 = Binary read y$6 === read $7
   If (read $8) then:bb2 else:bb1
 bb2:
   predecessor blocks: bb0
-  [5] Reassign mutate x$9 = 3
+  [5] Reassign mutate x$1 = 3
   Goto bb1
 bb1:
   predecessor blocks: bb2 bb0
-  x$10: phi(bb2: x$9, bb0: x$5)
-  [6] Reassign mutate y$11 = read x$10
+  [6] Reassign mutate y$11 = read x$1
   Return
 ```
 
@@ -38,13 +37,13 @@ bb1:
 
 ```javascript
 function foo$0() {
-  let x$5 = 1;
+  let x$1 = 1;
   let y$6 = 2;
   bb1: if (y$6 === 2) {
-    x$9 = 3;
+    x$1 = 3;
   }
 
-  y$11 = x$10;
+  y$11 = x$1;
   return;
 }
 
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-for.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-for.expect.md
index dfe24fe2df..d3c9fc45f6 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-for.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-for.expect.md
@@ -16,29 +16,28 @@ function foo() {
 
 ```
 bb0:
-  [1] Let mutate x$5 = 0
+  [1] Let mutate x$1 = 0
   Goto bb1
 bb1:
   predecessor blocks: bb0 bb4
-  x$7: phi(bb0: x$5, bb4: x$10)
   [2] Const mutate $6 = 10
-  [3] Const mutate $8 = Binary read x$7 < read $6
+  [3] Const mutate $8 = Binary read x$1 < read $6
   If (read $8) then:bb4 else:bb2
 bb4:
   predecessor blocks: bb1
   [4] Const mutate $9 = 1
-  [5] Reassign mutate x$10 = Binary read x$7 + read $9
+  [5] Reassign mutate x$1 = Binary read x$1 + read $9
   Goto bb1
 bb2:
   predecessor blocks: bb1
-  Return read x$7
+  Return read x$1
 ```
 
 ## Code
 
 ```javascript
 function foo$0() {
-  let x$5 = 0;
+  let x$1 = 0;
 }
 
 ```
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-objectexpression-phi.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-objectexpression-phi.expect.md
index 8729e4112b..05faad4bfc 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-objectexpression-phi.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-objectexpression-phi.expect.md
@@ -22,24 +22,22 @@ function foo() {
 
 ```
 bb0:
-  [1] Let mutate x$6 = 1
-  [2] Let mutate y$7 = 2
+  [1] Let mutate x$1 = 1
+  [2] Let mutate y$2 = 2
   [3] Const mutate $8 = 1
-  [4] Const mutate $9 = Binary read x$6 > read $8
+  [4] Const mutate $9 = Binary read x$1 > read $8
   If (read $9) then:bb2 else:bb3
 bb2:
   predecessor blocks: bb0
-  [5] Reassign mutate x$10 = 2
+  [5] Reassign mutate x$1 = 2
   Goto bb1
 bb3:
   predecessor blocks: bb0
-  [6] Reassign mutate y$11 = 3
+  [6] Reassign mutate y$2 = 3
   Goto bb1
 bb1:
   predecessor blocks: bb2 bb3
-  x$12: phi(bb2: x$10, bb3: x$6)
-  y$13: phi(bb2: y$7, bb3: y$11)
-  [7] Let mutate t$14 = Object { x: read x$12, y: read y$13 }
+  [7] Let mutate t$14 = Object { x: read x$1, y: read y$2 }
   Return freeze t$14
 ```
 
@@ -47,17 +45,17 @@ bb1:
 
 ```javascript
 function foo$0() {
-  let x$6 = 1;
-  let y$7 = 2;
-  bb1: if (x$6 > 1) {
-    x$10 = 2;
+  let x$1 = 1;
+  let y$2 = 2;
+  bb1: if (x$1 > 1) {
+    x$1 = 2;
   } else {
-    y$11 = 3;
+    y$2 = 3;
   }
 
   let t$14 = {
-    x: x$12,
-    y: y$13,
+    x: x$1,
+    y: y$2,
   };
   return t$14;
 }
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-return.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-return.expect.md
index d291e97cef..09cc1158a0 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-return.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-return.expect.md
@@ -17,30 +17,29 @@ function foo() {
 
 ```
 bb0:
-  [1] Let mutate x$4 = 1
+  [1] Let mutate x$1 = 1
   [2] Const mutate $5 = 1
-  [3] Const mutate $6 = Binary read x$4 === read $5
+  [3] Const mutate $6 = Binary read x$1 === read $5
   If (read $6) then:bb2 else:bb1
 bb2:
   predecessor blocks: bb0
-  [4] Reassign mutate x$7 = 2
+  [4] Reassign mutate x$1 = 2
   Goto bb1
 bb1:
   predecessor blocks: bb2 bb0
-  x$8: phi(bb2: x$7, bb0: x$4)
-  Return read x$8
+  Return read x$1
 ```
 
 ## Code
 
 ```javascript
 function foo$0() {
-  let x$4 = 1;
-  bb1: if (x$4 === 1) {
-    x$7 = 2;
+  let x$1 = 1;
+  bb1: if (x$1 === 1) {
+    x$1 = 2;
   }
 
-  return x$8;
+  return x$1;
 }
 
 ```
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-shadowing.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-shadowing.expect.md
new file mode 100644
index 0000000000..f210b0f70b
--- /dev/null
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-shadowing.expect.md
@@ -0,0 +1,73 @@
+
+## Input
+
+```javascript
+function log() {}
+
+function Foo(cond) {
+  let str = "";
+  if (cond) {
+    let str = "other test";
+    log(str);
+  } else {
+    str = "fallthrough test";
+  }
+  log(str);
+}
+
+```
+
+## HIR
+
+```
+bb0:
+  Return
+```
+
+## Code
+
+```javascript
+function log$0() {
+  return;
+}
+
+```
+## HIR
+
+```
+bb0:
+  [1] Let mutate str$2 = ""
+  If (read cond$5) then:bb2 else:bb3
+bb2:
+  predecessor blocks: bb0
+  [2] Let mutate str$7 = "other test"
+  [3] Call mutate log$4(read str$7)
+  Goto bb1
+bb3:
+  predecessor blocks: bb0
+  [4] Reassign mutate str$2 = "fallthrough test"
+  Goto bb1
+bb1:
+  predecessor blocks: bb2 bb3
+  [5] Call mutate log$4(read str$2)
+  Return
+```
+
+## Code
+
+```javascript
+function Foo$0(cond$5) {
+  let str$2 = "";
+  bb1: if (cond$5) {
+    let str$7 = "other test";
+    log$4(str$7);
+  } else {
+    str$2 = "fallthrough test";
+  }
+
+  log$4(str$2);
+  return;
+}
+
+```
+      
\ No newline at end of file
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-shadowing.js b/compiler/forget/src/__tests__/fixtures/hir/ssa-shadowing.js
new file mode 100644
index 0000000000..5fd9bb75d2
--- /dev/null
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-shadowing.js
@@ -0,0 +1,12 @@
+function log() {}
+
+function Foo(cond) {
+  let str = "";
+  if (cond) {
+    let str = "other test";
+    log(str);
+  } else {
+    str = "fallthrough test";
+  }
+  log(str);
+}
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-simple-phi.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-simple-phi.expect.md
index c60ef6bdb5..a4e9a1d1b8 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-simple-phi.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-simple-phi.expect.md
@@ -26,16 +26,15 @@ bb0:
   If (read $7) then:bb2 else:bb3
 bb2:
   predecessor blocks: bb0
-  [4] Reassign mutate y$8 = 1
+  [4] Reassign mutate y$1 = 1
   Goto bb1
 bb3:
   predecessor blocks: bb0
-  [5] Reassign mutate y$9 = 2
+  [5] Reassign mutate y$1 = 2
   Goto bb1
 bb1:
   predecessor blocks: bb2 bb3
-  y$10: phi(bb2: y$8, bb3: y$9)
-  [6] Let mutate x$11 = read y$10
+  [6] Let mutate x$11 = read y$1
   Return
 ```
 
@@ -45,12 +44,12 @@ bb1:
 function foo$0() {
   let y$5 = 2;
   bb1: if (y$5 > 1) {
-    y$8 = 1;
+    y$1 = 1;
   } else {
-    y$9 = 2;
+    y$1 = 2;
   }
 
-  let x$11 = y$10;
+  let x$11 = y$1;
   return;
 }
 
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-switch.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-switch.expect.md
index cf3506a2dd..34e0f1cf89 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-switch.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-switch.expect.md
@@ -40,22 +40,21 @@ bb0:
 bb5:
   predecessor blocks: bb0
   [6] Const mutate $15 = 1
-  [7] Reassign mutate x$16 = Binary read x$10 + read $15
+  [7] Reassign mutate x$1 = Binary read x$10 + read $15
   Goto bb1
 bb3:
   predecessor blocks: bb0
   [8] Const mutate $17 = 2
-  [9] Reassign mutate x$18 = Binary read x$10 + read $17
+  [9] Reassign mutate x$1 = Binary read x$10 + read $17
   Goto bb1
 bb2:
   predecessor blocks: bb0
   [10] Const mutate $19 = 3
-  [11] Reassign mutate x$20 = Binary read x$10 + read $19
+  [11] Reassign mutate x$1 = Binary read x$10 + read $19
   Goto bb1
 bb1:
   predecessor blocks: bb5 bb3 bb2
-  x$21: phi(bb5: x$16, bb3: x$18, bb2: x$20)
-  [12] Let mutate y$22 = read x$21
+  [12] Let mutate y$22 = read x$1
   Return
 ```
 
@@ -66,21 +65,21 @@ function foo$0() {
   let x$10 = 1;
   bb1: switch (x$10) {
     case x$10 === 1: {
-      x$16 = x$10 + 1;
+      x$1 = x$10 + 1;
       break bb1;
     }
 
     case x$10 === 2: {
-      x$18 = x$10 + 2;
+      x$1 = x$10 + 2;
       break bb1;
     }
 
     default: {
-      x$20 = x$10 + 3;
+      x$1 = x$10 + 3;
     }
   }
 
-  let y$22 = x$21;
+  let y$22 = x$1;
   return;
 }
 
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-throw.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-throw.expect.md
index 03269a912a..82958321a0 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-throw.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-throw.expect.md
@@ -16,30 +16,29 @@ function foo() {
 
 ```
 bb0:
-  [1] Let mutate x$4 = 1
+  [1] Let mutate x$1 = 1
   [2] Const mutate $5 = 1
-  [3] Const mutate $6 = Binary read x$4 === read $5
+  [3] Const mutate $6 = Binary read x$1 === read $5
   If (read $6) then:bb2 else:bb1
 bb2:
   predecessor blocks: bb0
-  [4] Reassign mutate x$7 = 2
+  [4] Reassign mutate x$1 = 2
   Goto bb1
 bb1:
   predecessor blocks: bb2 bb0
-  x$8: phi(bb2: x$7, bb0: x$4)
-  Throw read x$8
+  Throw read x$1
 ```
 
 ## Code
 
 ```javascript
 function foo$0() {
-  let x$4 = 1;
-  bb1: if (x$4 === 1) {
-    x$7 = 2;
+  let x$1 = 1;
+  bb1: if (x$1 === 1) {
+    x$1 = 2;
   }
 
-  throw x$8;
+  throw x$1;
 }
 
 ```
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-while.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-while.expect.md
index 7c76dda790..1c723cef31 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-while.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-while.expect.md
@@ -17,29 +17,28 @@ function foo() {
 
 ```
 bb0:
-  [1] Let mutate x$5 = 1
+  [1] Let mutate x$1 = 1
   Goto bb1
 bb1:
   predecessor blocks: bb0 bb3
-  x$7: phi(bb0: x$5, bb3: x$10)
   [2] Const mutate $6 = 10
-  [3] Const mutate $8 = Binary read x$7 < read $6
+  [3] Const mutate $8 = Binary read x$1 < read $6
   If (read $8) then:bb3 else:bb2
 bb3:
   predecessor blocks: bb1
   [4] Const mutate $9 = 1
-  [5] Reassign mutate x$10 = Binary read x$7 + read $9
+  [5] Reassign mutate x$1 = Binary read x$1 + read $9
   Goto bb1
 bb2:
   predecessor blocks: bb1
-  Return read x$7
+  Return read x$1
 ```
 
 ## Code
 
 ```javascript
 function foo$0() {
-  let x$5 = 1;
+  let x$1 = 1;
 }
 
 ```
diff --git a/compiler/forget/src/__tests__/fixtures/hir/switch-non-final-default.expect.md b/compiler/forget/src/__tests__/fixtures/hir/switch-non-final-default.expect.md
index 9e8546f4d6..ab7d946d2d 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/switch-non-final-default.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/switch-non-final-default.expect.md
@@ -33,7 +33,7 @@ function Component(props) {
 ```
 bb0:
   [1] Let mutate x$10[1:6] = Array []
-  [2] Let mutate y$11 = undefined
+  [2] Let mutate y$3 = undefined
   [3] Const mutate $12 = false
   [4] Const mutate $13 = true
   [5] Const mutate $14 = 1
@@ -45,18 +45,17 @@ bb0:
 bb6:
   predecessor blocks: bb0
   [6] Call mutate x$10.push(read props$9.p2)
-  [7] Reassign mutate y$15 = Array []
+  [7] Reassign mutate y$3 = Array []
   Goto bb1
 bb2:
   predecessor blocks: bb0
-  [8] Reassign mutate y$16 = read x$10
+  [8] Reassign mutate y$3 = read x$10
   Goto bb1
 bb1:
   predecessor blocks: bb0 bb6 bb2
-  y$20: phi(bb0: y$11, bb6: y$15, bb2: y$16)
   [9] Const mutate child$19 = JSX <read Component$0 data={freeze x$10} ></read Component$0>
-  [10] Call read y$20.push(read props$9.p4)
-  [11] Const mutate $22 = JSX <read Component$0 data={freeze y$20} >{read child$19}</read Component$0>
+  [10] Call read y$3.push(read props$9.p4)
+  [11] Const mutate $22 = JSX <read Component$0 data={freeze y$3} >{read child$19}</read Component$0>
   Return read $22
 ```
 
@@ -65,7 +64,7 @@ bb1:
 ```javascript
 function Component$0(props$9) {
   let x$10 = [];
-  let y$11 = undefined;
+  let y$3 = undefined;
   bb1: switch (props$9.p0) {
     case 1: {
       break bb1;
@@ -73,7 +72,7 @@ function Component$0(props$9) {
 
     case true: {
       x$10.push(props$9.p2);
-      y$15 = [];
+      y$3 = [];
       break bb1;
     }
 
@@ -82,13 +81,13 @@ function Component$0(props$9) {
     }
 
     case false: {
-      y$16 = x$10;
+      y$3 = x$10;
     }
   }
 
   const child$19 = <Component$0 data={x$10}></Component$0>;
-  y$20.push(props$9.p4);
-  return <Component$0 data={y$20}>{child$19}</Component$0>;
+  y$3.push(props$9.p4);
+  return <Component$0 data={y$3}>{child$19}</Component$0>;
 }
 
 ```
diff --git a/compiler/forget/src/__tests__/fixtures/hir/switch.expect.md b/compiler/forget/src/__tests__/fixtures/hir/switch.expect.md
index 385a690ad2..7ff960925a 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/switch.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/switch.expect.md
@@ -29,7 +29,7 @@ function Component(props) {
 ```
 bb0:
   [1] Let mutate x$9[1:6] = Array []
-  [2] Let mutate y$10 = undefined
+  [2] Let mutate y$3 = undefined
   [3] Const mutate $11 = false
   [4] Const mutate $12 = true
   Switch (read props$8.p0)
@@ -44,14 +44,13 @@ bb4:
   Goto bb2
 bb2:
   predecessor blocks: bb4 bb0
-  [8] Reassign mutate y$15 = read x$9
+  [8] Reassign mutate y$3 = read x$9
   Goto bb1
 bb1:
   predecessor blocks: bb2 bb0
-  y$20: phi(bb2: y$15, bb0: y$10)
   [9] Const mutate child$19 = JSX <read Component$0 data={freeze x$9} ></read Component$0>
-  [10] Call read y$20.push(read props$8.p4)
-  [11] Const mutate $23 = JSX <read Component$0 data={read y$20} >{read child$19}</read Component$0>
+  [10] Call read y$3.push(read props$8.p4)
+  [11] Const mutate $23 = JSX <read Component$0 data={read y$3} >{read child$19}</read Component$0>
   Return read $23
 ```
 
@@ -60,7 +59,7 @@ bb1:
 ```javascript
 function Component$0(props$8) {
   let x$9 = [];
-  let y$10 = undefined;
+  let y$3 = undefined;
   bb1: switch (props$8.p0) {
     case true: {
       x$9.push(props$8.p2);
@@ -69,13 +68,13 @@ function Component$0(props$8) {
     }
 
     case false: {
-      y$15 = x$9;
+      y$3 = x$9;
     }
   }
 
   const child$19 = <Component$0 data={x$9}></Component$0>;
-  y$20.push(props$8.p4);
-  return <Component$0 data={y$20}>{child$19}</Component$0>;
+  y$3.push(props$8.p4);
+  return <Component$0 data={y$3}>{child$19}</Component$0>;
 }
 
 ```
diff --git a/compiler/forget/src/__tests__/hir-test.ts b/compiler/forget/src/__tests__/hir-test.ts
index 80b68a7c14..b9739c4572 100644
--- a/compiler/forget/src/__tests__/hir-test.ts
+++ b/compiler/forget/src/__tests__/hir-test.ts
@@ -22,6 +22,7 @@ import { HIRFunction } from "../HIR/HIR";
 import { Environment } from "../HIR/HIRBuilder";
 import { inferMutableRanges } from "../HIR/InferMutableLifetimes";
 import inferReferenceEffects from "../HIR/InferReferenceEffects";
+import leaveSSA from "../HIR/LeaveSSA";
 import printHIR from "../HIR/PrintHIR";
 import generateTestsFromFixtures from "./test-utils/generateTestsFromFixtures";
 
@@ -68,6 +69,7 @@ describe("React Forget (HIR version)", () => {
             eliminateRedundantPhi(ir);
             inferReferenceEffects(ir);
             inferMutableRanges(ir);
+            leaveSSA(ir);
             // const lifetimeGraph = buildDefUseGraph(ir);
             const textHIR = printHIR(ir.body);
             // const textLifetimeGraph = printGraph(lifetimeGraph);