diff --git a/tests/baselines/reference/controlFlowTruthiness.js b/tests/baselines/reference/controlFlowTruthiness.js
new file mode 100644
index 0000000000..b595bcbd18
--- /dev/null
+++ b/tests/baselines/reference/controlFlowTruthiness.js
@@ -0,0 +1,134 @@
+//// [controlFlowTruthiness.ts]
+
+declare function foo(): string | undefined;
+
+function f1() {
+    let x = foo();
+    if (x) {
+        x; // string
+    }
+    else {
+        x; // string | undefined
+    }
+}
+
+function f2() {
+    let x: string | undefined;
+    x = foo();
+    if (x) {
+        x; // string
+    }
+    else {
+        x; // string | undefined
+    }
+}
+
+function f3() {
+    let x: string | undefined;
+    if (x = foo()) {
+        x; // string
+    }
+    else {
+        x; // string | undefined
+    }
+}
+
+function f4() {
+    let x: string | undefined;
+    if (!(x = foo())) {
+        x; // string | undefined
+    }
+    else {
+        x; // string
+    }
+}
+
+function f5() {
+    let x: string | undefined;
+    let y: string | undefined;
+    if (x = y = foo()) {
+        x; // string
+        y; // string | undefined
+    }
+    else {
+        x; // string | undefined
+        y; // string | undefined
+    }
+}
+
+function f6() {
+    let x: string | undefined;
+    let y: string | undefined;
+    if (x = foo(), y = foo()) {
+        x; // string | undefined
+        y; // string
+    }
+    else {
+        x; // string | undefined
+        y; // string | undefined
+    }
+}
+
+
+//// [controlFlowTruthiness.js]
+function f1() {
+    var x = foo();
+    if (x) {
+        x; // string
+    }
+    else {
+        x; // string | undefined
+    }
+}
+function f2() {
+    var x;
+    x = foo();
+    if (x) {
+        x; // string
+    }
+    else {
+        x; // string | undefined
+    }
+}
+function f3() {
+    var x;
+    if (x = foo()) {
+        x; // string
+    }
+    else {
+        x; // string | undefined
+    }
+}
+function f4() {
+    var x;
+    if (!(x = foo())) {
+        x; // string | undefined
+    }
+    else {
+        x; // string
+    }
+}
+function f5() {
+    var x;
+    var y;
+    if (x = y = foo()) {
+        x; // string
+        y; // string | undefined
+    }
+    else {
+        x; // string | undefined
+        y; // string | undefined
+    }
+}
+function f6() {
+    var x;
+    var y;
+    if (x = foo(), y = foo()) {
+        x; // string | undefined
+        y; // string
+    }
+    else {
+        x; // string | undefined
+        y; // string | undefined
+    }
+}
diff --git a/tests/baselines/reference/controlFlowTruthiness.symbols b/tests/baselines/reference/controlFlowTruthiness.symbols
new file mode 100644
index 0000000000..37c1fb135f
--- /dev/null
+++ b/tests/baselines/reference/controlFlowTruthiness.symbols
@@ -0,0 +1,143 @@
+=== tests/cases/conformance/controlFlow/controlFlowTruthiness.ts ===
+
+declare function foo(): string | undefined;
+>foo : Symbol(foo, Decl(controlFlowTruthiness.ts, 0, 0))
+
+function f1() {
+>f1 : Symbol(f1, Decl(controlFlowTruthiness.ts, 1, 43))
+
+    let x = foo();
+>x : Symbol(x, Decl(controlFlowTruthiness.ts, 4, 7))
+>foo : Symbol(foo, Decl(controlFlowTruthiness.ts, 0, 0))
+
+    if (x) {
+>x : Symbol(x, Decl(controlFlowTruthiness.ts, 4, 7))
+
+        x; // string
+>x : Symbol(x, Decl(controlFlowTruthiness.ts, 4, 7))
+    }
+    else {
+        x; // string | undefined
+>x : Symbol(x, Decl(controlFlowTruthiness.ts, 4, 7))
+    }
+}
+
+function f2() {
+>f2 : Symbol(f2, Decl(controlFlowTruthiness.ts, 11, 1))
+
+    let x: string | undefined;
+>x : Symbol(x, Decl(controlFlowTruthiness.ts, 14, 7))
+
+    x = foo();
+>x : Symbol(x, Decl(controlFlowTruthiness.ts, 14, 7))
+>foo : Symbol(foo, Decl(controlFlowTruthiness.ts, 0, 0))
+
+    if (x) {
+>x : Symbol(x, Decl(controlFlowTruthiness.ts, 14, 7))
+
+        x; // string
+>x : Symbol(x, Decl(controlFlowTruthiness.ts, 14, 7))
+    }
+    else {
+        x; // string | undefined
+>x : Symbol(x, Decl(controlFlowTruthiness.ts, 14, 7))
+    }
+}
+
+function f3() {
+>f3 : Symbol(f3, Decl(controlFlowTruthiness.ts, 22, 1))
+
+    let x: string | undefined;
+>x : Symbol(x, Decl(controlFlowTruthiness.ts, 25, 7))
+
+    if (x = foo()) {
+>x : Symbol(x, Decl(controlFlowTruthiness.ts, 25, 7))
+>foo : Symbol(foo, Decl(controlFlowTruthiness.ts, 0, 0))
+
+        x; // string
+>x : Symbol(x, Decl(controlFlowTruthiness.ts, 25, 7))
+    }
+    else {
+        x; // string | undefined
+>x : Symbol(x, Decl(controlFlowTruthiness.ts, 25, 7))
+    }
+}
+
+function f4() {
+>f4 : Symbol(f4, Decl(controlFlowTruthiness.ts, 32, 1))
+
+    let x: string | undefined;
+>x : Symbol(x, Decl(controlFlowTruthiness.ts, 35, 7))
+
+    if (!(x = foo())) {
+>x : Symbol(x, Decl(controlFlowTruthiness.ts, 35, 7))
+>foo : Symbol(foo, Decl(controlFlowTruthiness.ts, 0, 0))
+
+        x; // string | undefined
+>x : Symbol(x, Decl(controlFlowTruthiness.ts, 35, 7))
+    }
+    else {
+        x; // string
+>x : Symbol(x, Decl(controlFlowTruthiness.ts, 35, 7))
+    }
+}
+
+function f5() {
+>f5 : Symbol(f5, Decl(controlFlowTruthiness.ts, 42, 1))
+
+    let x: string | undefined;
+>x : Symbol(x, Decl(controlFlowTruthiness.ts, 45, 7))
+
+    let y: string | undefined;
+>y : Symbol(y, Decl(controlFlowTruthiness.ts, 46, 7))
+
+    if (x = y = foo()) {
+>x : Symbol(x, Decl(controlFlowTruthiness.ts, 45, 7))
+>y : Symbol(y, Decl(controlFlowTruthiness.ts, 46, 7))
+>foo : Symbol(foo, Decl(controlFlowTruthiness.ts, 0, 0))
+
+        x; // string
+>x : Symbol(x, Decl(controlFlowTruthiness.ts, 45, 7))
+
+        y; // string | undefined
+>y : Symbol(y, Decl(controlFlowTruthiness.ts, 46, 7))
+    }
+    else {
+        x; // string | undefined
+>x : Symbol(x, Decl(controlFlowTruthiness.ts, 45, 7))
+
+        y; // string | undefined
+>y : Symbol(y, Decl(controlFlowTruthiness.ts, 46, 7))
+    }
+}
+
+function f6() {
+>f6 : Symbol(f6, Decl(controlFlowTruthiness.ts, 55, 1))
+
+    let x: string | undefined;
+>x : Symbol(x, Decl(controlFlowTruthiness.ts, 58, 7))
+
+    let y: string | undefined;
+>y : Symbol(y, Decl(controlFlowTruthiness.ts, 59, 7))
+
+    if (x = foo(), y = foo()) {
+>x : Symbol(x, Decl(controlFlowTruthiness.ts, 58, 7))
+>foo : Symbol(foo, Decl(controlFlowTruthiness.ts, 0, 0))
+>y : Symbol(y, Decl(controlFlowTruthiness.ts, 59, 7))
+>foo : Symbol(foo, Decl(controlFlowTruthiness.ts, 0, 0))
+
+        x; // string | undefined
+>x : Symbol(x, Decl(controlFlowTruthiness.ts, 58, 7))
+
+        y; // string
+>y : Symbol(y, Decl(controlFlowTruthiness.ts, 59, 7))
+    }
+    else {
+        x; // string | undefined
+>x : Symbol(x, Decl(controlFlowTruthiness.ts, 58, 7))
+
+        y; // string | undefined
+>y : Symbol(y, Decl(controlFlowTruthiness.ts, 59, 7))
+    }
+}
+
diff --git a/tests/baselines/reference/controlFlowTruthiness.types b/tests/baselines/reference/controlFlowTruthiness.types
new file mode 100644
index 0000000000..2d35856fe8
--- /dev/null
+++ b/tests/baselines/reference/controlFlowTruthiness.types
@@ -0,0 +1,160 @@
+=== tests/cases/conformance/controlFlow/controlFlowTruthiness.ts ===
+
+declare function foo(): string | undefined;
+>foo : () => string | undefined
+
+function f1() {
+>f1 : () => void
+
+    let x = foo();
+>x : string | undefined
+>foo() : string | undefined
+>foo : () => string | undefined
+
+    if (x) {
+>x : string | undefined
+
+        x; // string
+>x : string
+    }
+    else {
+        x; // string | undefined
+>x : string | undefined
+    }
+}
+
+function f2() {
+>f2 : () => void
+
+    let x: string | undefined;
+>x : string | undefined
+
+    x = foo();
+>x = foo() : string | undefined
+>x : string | undefined
+>foo() : string | undefined
+>foo : () => string | undefined
+
+    if (x) {
+>x : string | undefined
+
+        x; // string
+>x : string
+    }
+    else {
+        x; // string | undefined
+>x : string | undefined
+    }
+}
+
+function f3() {
+>f3 : () => void
+
+    let x: string | undefined;
+>x : string | undefined
+
+    if (x = foo()) {
+>x = foo() : string | undefined
+>x : string | undefined
+>foo() : string | undefined
+>foo : () => string | undefined
+
+        x; // string
+>x : string
+    }
+    else {
+        x; // string | undefined
+>x : string | undefined
+    }
+}
+
+function f4() {
+>f4 : () => void
+
+    let x: string | undefined;
+>x : string | undefined
+
+    if (!(x = foo())) {
+>!(x = foo()) : boolean
+>(x = foo()) : string | undefined
+>x = foo() : string | undefined
+>x : string | undefined
+>foo() : string | undefined
+>foo : () => string | undefined
+
+        x; // string | undefined
+>x : string | undefined
+    }
+    else {
+        x; // string
+>x : string
+    }
+}
+
+function f5() {
+>f5 : () => void
+
+    let x: string | undefined;
+>x : string | undefined
+
+    let y: string | undefined;
+>y : string | undefined
+
+    if (x = y = foo()) {
+>x = y = foo() : string | undefined
+>x : string | undefined
+>y = foo() : string | undefined
+>y : string | undefined
+>foo() : string | undefined
+>foo : () => string | undefined
+
+        x; // string
+>x : string
+
+        y; // string | undefined
+>y : string | undefined
+    }
+    else {
+        x; // string | undefined
+>x : string | undefined
+
+        y; // string | undefined
+>y : string | undefined
+    }
+}
+
+function f6() {
+>f6 : () => void
+
+    let x: string | undefined;
+>x : string | undefined
+
+    let y: string | undefined;
+>y : string | undefined
+
+    if (x = foo(), y = foo()) {
+>x = foo(), y = foo() : string | undefined
+>x = foo() : string | undefined
+>x : string | undefined
+>foo() : string | undefined
+>foo : () => string | undefined
+>y = foo() : string | undefined
+>y : string | undefined
+>foo() : string | undefined
+>foo : () => string | undefined
+
+        x; // string | undefined
+>x : string | undefined
+
+        y; // string
+>y : string
+    }
+    else {
+        x; // string | undefined
+>x : string | undefined
+
+        y; // string | undefined
+>y : string | undefined
+    }
+}
+
diff --git a/tests/cases/conformance/controlFlow/controlFlowTruthiness.ts b/tests/cases/conformance/controlFlow/controlFlowTruthiness.ts
new file mode 100644
index 0000000000..ba1947da13
--- /dev/null
+++ b/tests/cases/conformance/controlFlow/controlFlowTruthiness.ts
@@ -0,0 +1,70 @@
+// @strictNullChecks: true
+
+declare function foo(): string | undefined;
+
+function f1() {
+    let x = foo();
+    if (x) {
+        x; // string
+    }
+    else {
+        x; // string | undefined
+    }
+}
+
+function f2() {
+    let x: string | undefined;
+    x = foo();
+    if (x) {
+        x; // string
+    }
+    else {
+        x; // string | undefined
+    }
+}
+
+function f3() {
+    let x: string | undefined;
+    if (x = foo()) {
+        x; // string
+    }
+    else {
+        x; // string | undefined
+    }
+}
+
+function f4() {
+    let x: string | undefined;
+    if (!(x = foo())) {
+        x; // string | undefined
+    }
+    else {
+        x; // string
+    }
+}
+
+function f5() {
+    let x: string | undefined;
+    let y: string | undefined;
+    if (x = y = foo()) {
+        x; // string
+        y; // string | undefined
+    }
+    else {
+        x; // string | undefined
+        y; // string | undefined
+    }
+}
+
+function f6() {
+    let x: string | undefined;
+    let y: string | undefined;
+    if (x = foo(), y = foo()) {
+        x; // string | undefined
+        y; // string
+    }
+    else {
+        x; // string | undefined
+        y; // string | undefined
+    }
+}