diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index ad3f3b71f29fb..07bba3dd0b238 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -3057,9 +3057,20 @@ namespace ts {
         function resolveExternalModuleSymbol(moduleSymbol: Symbol | undefined, dontResolveAlias?: boolean): Symbol | undefined;
         function resolveExternalModuleSymbol(moduleSymbol: Symbol, dontResolveAlias?: boolean): Symbol {
             if (moduleSymbol) {
+                const links = getSymbolLinks(moduleSymbol);
+                if (!dontResolveAlias) {
+                    links.resolvedExternalModuleSymbol = "circular";
+                }
                 const exportEquals = resolveSymbol(moduleSymbol.exports!.get(InternalSymbolName.ExportEquals), dontResolveAlias);
                 const exported = getCommonJsExportEquals(getMergedSymbol(exportEquals), getMergedSymbol(moduleSymbol));
-                return getMergedSymbol(exported) || moduleSymbol;
+                const result = getMergedSymbol(exported) || moduleSymbol;
+                if (!dontResolveAlias) {
+                    // we "cache" this result, but because both the input _and_ the output are mergeable, literally every call could need
+                    // a different result, assuming the inputs and outputs get merged with. So instead we just use this as a flag that
+                    // export assignment resolution has occured on this symbol at least once. (because it might happen many times!)
+                    links.resolvedExternalModuleSymbol = result;
+                }
+                return result;
             }
             return undefined!;
         }
@@ -5531,7 +5542,7 @@ namespace ts {
                 function serializeSymbolWorker(symbol: Symbol, isPrivate: boolean, propertyAsAlias: boolean) {
                     const symbolName = unescapeLeadingUnderscores(symbol.escapedName);
                     const isDefault = symbol.escapedName === InternalSymbolName.Default;
-                    if (isStringANonContextualKeyword(symbolName) && !isDefault) {
+                    if ((isStringANonContextualKeyword(symbolName) || !isIdentifierText(symbolName, languageVersion)) && !isDefault && symbol.escapedName !== InternalSymbolName.ExportEquals) {
                         // Oh no. We cannot use this symbol's name as it's name... It's likely some jsdoc had an invalid name like `export` or `default` :(
                         context.encounteredError = true;
                         // TODO: Issue error via symbol tracker?
@@ -5682,7 +5693,8 @@ namespace ts {
                 }
 
                 function getNamespaceMembersForSerialization(symbol: Symbol) {
-                    return !symbol.exports ? [] : filter(arrayFrom((symbol.exports).values()), p => !((p.flags & SymbolFlags.Prototype) || (p.escapedName === "prototype")));
+                    const exports = getExportsOfSymbol(symbol);
+                    return !exports ? [] : filter(arrayFrom((exports).values()), p => !((p.flags & SymbolFlags.Prototype) || (p.escapedName === "prototype")));
                 }
 
                 function isTypeOnlyNamespace(symbol: Symbol) {
@@ -8884,6 +8896,17 @@ namespace ts {
         function getResolvedMembersOrExportsOfSymbol(symbol: Symbol, resolutionKind: MembersOrExportsResolutionKind): UnderscoreEscapedMap<Symbol> {
             const links = getSymbolLinks(symbol);
             if (!links[resolutionKind]) {
+                // We _must_ resolve any possible commonjs export assignments _before_ merging in late bound members, as cjs export assignments may cause
+                // things to be merged (?!?) into this symbol; moreover, we _can't_ resolve those export assignments if we're already resolving the containing
+                // module (as then we'll issue a circularity error)
+                const p = symbol.valueDeclaration?.parent;
+                if (p && isSourceFile(p) && p.symbol && !getSymbolLinks(p.symbol).resolvedExternalModuleSymbol) {
+                    const exported = resolveExternalModuleSymbol(p.symbol);
+                    const targetLinks = exported && getSymbolLinks(exported);
+                    if (targetLinks && targetLinks[resolutionKind]) {
+                        return links[resolutionKind] = targetLinks[resolutionKind]!;
+                    }
+                }
                 const isStatic = resolutionKind === MembersOrExportsResolutionKind.resolvedExports;
                 const earlySymbols = !isStatic ? symbol.members :
                     symbol.flags & SymbolFlags.Module ? getExportsOfModuleWorker(symbol) :
@@ -35082,8 +35105,8 @@ namespace ts {
             }
         }
 
-        function createTypeOfDeclaration(declarationIn: AccessorDeclaration | VariableLikeDeclaration | PropertyAccessExpression, enclosingDeclaration: Node, flags: NodeBuilderFlags, tracker: SymbolTracker, addUndefined?: boolean) {
-            const declaration = getParseTreeNode(declarationIn, isVariableLikeOrAccessor);
+        function createTypeOfDeclaration(declarationIn: AccessorDeclaration | VariableLikeDeclaration | PropertyAccessExpression | ElementAccessExpression | BinaryExpression, enclosingDeclaration: Node, flags: NodeBuilderFlags, tracker: SymbolTracker, addUndefined?: boolean) {
+            const declaration = getParseTreeNode(declarationIn, isPossiblyPropertyLikeDeclaration);
             if (!declaration) {
                 return createToken(SyntaxKind.AnyKeyword) as KeywordTypeNode;
             }
diff --git a/src/compiler/transformers/declarations.ts b/src/compiler/transformers/declarations.ts
index 00417535145b0..605e441da67b5 100644
--- a/src/compiler/transformers/declarations.ts
+++ b/src/compiler/transformers/declarations.ts
@@ -1157,13 +1157,20 @@ namespace ts {
                         fakespace.locals = createSymbolTable(props);
                         fakespace.symbol = props[0].parent!;
                         const declarations = mapDefined(props, p => {
-                            if (!isPropertyAccessExpression(p.valueDeclaration)) {
-                                return undefined; // TODO GH#33569: Handle element access expressions that created late bound names (rather than silently omitting them)
+                            if (!isPropertyAccessExpression(p.valueDeclaration) && !isElementAccessExpression(p.valueDeclaration) && !isBinaryExpression(p.valueDeclaration)) {
+                                return undefined;
+                            }
+                            if (hasDynamicName(p.valueDeclaration) && !resolver.isLateBound(getParseTreeNode(p.valueDeclaration) as Declaration)) {
+                                return undefined;
+                            }
+                            const name = unescapeLeadingUnderscores(p.escapedName);
+                            if (!isIdentifierText(name, ScriptTarget.ES3)) {
+                                return undefined; // TODO: Rather than quietly eliding (as is current behavior), maybe we should issue errors?
                             }
                             getSymbolAccessibilityDiagnostic = createGetSymbolAccessibilityDiagnosticForNode(p.valueDeclaration);
                             const type = resolver.createTypeOfDeclaration(p.valueDeclaration, fakespace, declarationEmitNodeBuilderFlags, symbolTracker);
                             getSymbolAccessibilityDiagnostic = oldDiag;
-                            const varDecl = createVariableDeclaration(unescapeLeadingUnderscores(p.escapedName), type, /*initializer*/ undefined);
+                            const varDecl = createVariableDeclaration(name, type, /*initializer*/ undefined);
                             return createVariableStatement(/*modifiers*/ undefined, createVariableDeclarationList([varDecl]));
                         });
                         const namespaceDecl = createModuleDeclaration(/*decorators*/ undefined, ensureModifiers(input), input.name!, createModuleBlock(declarations), NodeFlags.Namespace);
diff --git a/src/compiler/transformers/declarations/diagnostics.ts b/src/compiler/transformers/declarations/diagnostics.ts
index ac44f7efd15e5..1b7827f552f07 100644
--- a/src/compiler/transformers/declarations/diagnostics.ts
+++ b/src/compiler/transformers/declarations/diagnostics.ts
@@ -27,7 +27,9 @@ namespace ts {
         | TypeAliasDeclaration
         | ConstructorDeclaration
         | IndexSignatureDeclaration
-        | PropertyAccessExpression;
+        | PropertyAccessExpression
+        | ElementAccessExpression
+        | BinaryExpression;
 
     export function canProduceDiagnostics(node: Node): node is DeclarationDiagnosticProducing {
         return isVariableDeclaration(node) ||
@@ -48,7 +50,9 @@ namespace ts {
             isTypeAliasDeclaration(node) ||
             isConstructorDeclaration(node) ||
             isIndexSignatureDeclaration(node) ||
-            isPropertyAccessExpression(node);
+            isPropertyAccessExpression(node) ||
+            isElementAccessExpression(node) ||
+            isBinaryExpression(node);
     }
 
     export function createGetSymbolAccessibilityDiagnosticForNodeName(node: DeclarationDiagnosticProducing) {
@@ -125,7 +129,7 @@ namespace ts {
     }
 
     export function createGetSymbolAccessibilityDiagnosticForNode(node: DeclarationDiagnosticProducing): (symbolAccessibilityResult: SymbolAccessibilityResult) => SymbolAccessibilityDiagnostic | undefined {
-        if (isVariableDeclaration(node) || isPropertyDeclaration(node) || isPropertySignature(node) || isPropertyAccessExpression(node) || isBindingElement(node) || isConstructorDeclaration(node)) {
+        if (isVariableDeclaration(node) || isPropertyDeclaration(node) || isPropertySignature(node) || isPropertyAccessExpression(node) || isElementAccessExpression(node) || isBinaryExpression(node) || isBindingElement(node) || isConstructorDeclaration(node)) {
             return getVariableDeclarationTypeVisibilityError;
         }
         else if (isSetAccessor(node) || isGetAccessor(node)) {
@@ -166,7 +170,7 @@ namespace ts {
             }
             // This check is to ensure we don't report error on constructor parameter property as that error would be reported during parameter emit
             // The only exception here is if the constructor was marked as private. we are not emitting the constructor parameters at all.
-            else if (node.kind === SyntaxKind.PropertyDeclaration || node.kind === SyntaxKind.PropertyAccessExpression || node.kind === SyntaxKind.PropertySignature ||
+            else if (node.kind === SyntaxKind.PropertyDeclaration || node.kind === SyntaxKind.PropertyAccessExpression || node.kind === SyntaxKind.ElementAccessExpression || node.kind === SyntaxKind.BinaryExpression || node.kind === SyntaxKind.PropertySignature ||
                 (node.kind === SyntaxKind.Parameter && hasModifier(node.parent, ModifierFlags.Private))) {
                 // TODO(jfreeman): Deal with computed properties in error reporting.
                 if (hasModifier(node, ModifierFlags.Static)) {
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index 9b913c2f17d00..ba9affda43757 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -3920,7 +3920,7 @@ namespace ts {
         isOptionalUninitializedParameterProperty(node: ParameterDeclaration): boolean;
         isExpandoFunctionDeclaration(node: FunctionDeclaration): boolean;
         getPropertiesOfContainerFunction(node: Declaration): Symbol[];
-        createTypeOfDeclaration(declaration: AccessorDeclaration | VariableLikeDeclaration | PropertyAccessExpression, enclosingDeclaration: Node, flags: NodeBuilderFlags, tracker: SymbolTracker, addUndefined?: boolean): TypeNode | undefined;
+        createTypeOfDeclaration(declaration: AccessorDeclaration | VariableLikeDeclaration | PropertyAccessExpression | ElementAccessExpression | BinaryExpression, enclosingDeclaration: Node, flags: NodeBuilderFlags, tracker: SymbolTracker, addUndefined?: boolean): TypeNode | undefined;
         createReturnTypeOfSignatureDeclaration(signatureDeclaration: SignatureDeclaration, enclosingDeclaration: Node, flags: NodeBuilderFlags, tracker: SymbolTracker): TypeNode | undefined;
         createTypeOfExpression(expr: Expression, enclosingDeclaration: Node, flags: NodeBuilderFlags, tracker: SymbolTracker): TypeNode | undefined;
         createLiteralConstValue(node: VariableDeclaration | PropertyDeclaration | PropertySignature | ParameterDeclaration, tracker: SymbolTracker): Expression;
@@ -4094,6 +4094,7 @@ namespace ts {
         deferralParent?: Type;              // Source union/intersection of a deferred type
         cjsExportMerged?: Symbol;           // Version of the symbol with all non export= exports merged with the export= target
         typeOnlyDeclaration?: TypeOnlyCompatibleAliasDeclaration | false; // First resolved alias declaration that makes the symbol only usable in type constructs
+        resolvedExternalModuleSymbol?: Symbol | "circular";  // Cached result of `resolveExternalModuleSymbol`
     }
 
     /* @internal */
diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
index bdee20ef861bf..09e4f35388348 100644
--- a/src/compiler/utilities.ts
+++ b/src/compiler/utilities.ts
@@ -1296,6 +1296,10 @@ namespace ts {
         return isVariableLike(node) || isAccessor(node);
     }
 
+    export function isPossiblyPropertyLikeDeclaration(node: Node): node is AccessorDeclaration | VariableLikeDeclaration | PropertyAccessExpression | ElementAccessExpression {
+        return isVariableLikeOrAccessor(node) || isPropertyAccessExpression(node) || isElementAccessExpression(node) || isBinaryExpression(node);
+    }
+
     export function isVariableDeclarationInVariableStatement(node: VariableDeclaration) {
         return node.parent.kind === SyntaxKind.VariableDeclarationList
             && node.parent.parent.kind === SyntaxKind.VariableStatement;
diff --git a/tests/baselines/reference/lateBoundElementAccessAssignmentDeclarations.js b/tests/baselines/reference/lateBoundElementAccessAssignmentDeclarations.js
new file mode 100644
index 0000000000000..b32a31e9a3505
--- /dev/null
+++ b/tests/baselines/reference/lateBoundElementAccessAssignmentDeclarations.js
@@ -0,0 +1,40 @@
+//// [lateBoundElementAccessAssignmentDeclarations.ts]
+export function foo() {}
+foo.bar = 12;
+const _private = Symbol();
+foo[_private] = "ok";
+const strMem = "strMemName";
+foo[strMem] = "ok";
+const dashStrMem = "dashed-str-mem";
+foo[dashStrMem] = "ok";
+const numMem = 42;
+foo[numMem] = "ok";
+
+const x: string = foo[_private];
+const y: string = foo[strMem];
+const z: string = foo[numMem];
+const a: string = foo[dashStrMem];
+
+//// [lateBoundElementAccessAssignmentDeclarations.js]
+export function foo() { }
+foo.bar = 12;
+const _private = Symbol();
+foo[_private] = "ok";
+const strMem = "strMemName";
+foo[strMem] = "ok";
+const dashStrMem = "dashed-str-mem";
+foo[dashStrMem] = "ok";
+const numMem = 42;
+foo[numMem] = "ok";
+const x = foo[_private];
+const y = foo[strMem];
+const z = foo[numMem];
+const a = foo[dashStrMem];
+
+
+//// [lateBoundElementAccessAssignmentDeclarations.d.ts]
+export declare function foo(): void;
+export declare namespace foo {
+    var bar: number;
+    var strMemName: string;
+}
diff --git a/tests/baselines/reference/lateBoundElementAccessAssignmentDeclarations.symbols b/tests/baselines/reference/lateBoundElementAccessAssignmentDeclarations.symbols
new file mode 100644
index 0000000000000..d407959b0c312
--- /dev/null
+++ b/tests/baselines/reference/lateBoundElementAccessAssignmentDeclarations.symbols
@@ -0,0 +1,58 @@
+=== tests/cases/compiler/lateBoundElementAccessAssignmentDeclarations.ts ===
+export function foo() {}
+>foo : Symbol(foo, Decl(lateBoundElementAccessAssignmentDeclarations.ts, 0, 0), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 0, 24), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 2, 26), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 4, 28), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 6, 36) ... and 1 more)
+
+foo.bar = 12;
+>foo.bar : Symbol(foo.bar, Decl(lateBoundElementAccessAssignmentDeclarations.ts, 0, 24))
+>foo : Symbol(foo, Decl(lateBoundElementAccessAssignmentDeclarations.ts, 0, 0), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 0, 24), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 2, 26), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 4, 28), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 6, 36) ... and 1 more)
+>bar : Symbol(foo.bar, Decl(lateBoundElementAccessAssignmentDeclarations.ts, 0, 24))
+
+const _private = Symbol();
+>_private : Symbol(_private, Decl(lateBoundElementAccessAssignmentDeclarations.ts, 2, 5))
+>Symbol : Symbol(Symbol, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.symbol.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --))
+
+foo[_private] = "ok";
+>foo : Symbol(foo, Decl(lateBoundElementAccessAssignmentDeclarations.ts, 0, 0), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 0, 24), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 2, 26), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 4, 28), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 6, 36) ... and 1 more)
+>_private : Symbol(_private, Decl(lateBoundElementAccessAssignmentDeclarations.ts, 2, 5))
+
+const strMem = "strMemName";
+>strMem : Symbol(strMem, Decl(lateBoundElementAccessAssignmentDeclarations.ts, 4, 5))
+
+foo[strMem] = "ok";
+>foo : Symbol(foo, Decl(lateBoundElementAccessAssignmentDeclarations.ts, 0, 0), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 0, 24), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 2, 26), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 4, 28), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 6, 36) ... and 1 more)
+>strMem : Symbol(strMem, Decl(lateBoundElementAccessAssignmentDeclarations.ts, 4, 5))
+
+const dashStrMem = "dashed-str-mem";
+>dashStrMem : Symbol(dashStrMem, Decl(lateBoundElementAccessAssignmentDeclarations.ts, 6, 5))
+
+foo[dashStrMem] = "ok";
+>foo : Symbol(foo, Decl(lateBoundElementAccessAssignmentDeclarations.ts, 0, 0), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 0, 24), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 2, 26), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 4, 28), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 6, 36) ... and 1 more)
+>dashStrMem : Symbol(dashStrMem, Decl(lateBoundElementAccessAssignmentDeclarations.ts, 6, 5))
+
+const numMem = 42;
+>numMem : Symbol(numMem, Decl(lateBoundElementAccessAssignmentDeclarations.ts, 8, 5))
+
+foo[numMem] = "ok";
+>foo : Symbol(foo, Decl(lateBoundElementAccessAssignmentDeclarations.ts, 0, 0), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 0, 24), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 2, 26), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 4, 28), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 6, 36) ... and 1 more)
+>numMem : Symbol(numMem, Decl(lateBoundElementAccessAssignmentDeclarations.ts, 8, 5))
+
+const x: string = foo[_private];
+>x : Symbol(x, Decl(lateBoundElementAccessAssignmentDeclarations.ts, 11, 5))
+>foo : Symbol(foo, Decl(lateBoundElementAccessAssignmentDeclarations.ts, 0, 0), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 0, 24), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 2, 26), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 4, 28), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 6, 36) ... and 1 more)
+>_private : Symbol(_private, Decl(lateBoundElementAccessAssignmentDeclarations.ts, 2, 5))
+
+const y: string = foo[strMem];
+>y : Symbol(y, Decl(lateBoundElementAccessAssignmentDeclarations.ts, 12, 5))
+>foo : Symbol(foo, Decl(lateBoundElementAccessAssignmentDeclarations.ts, 0, 0), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 0, 24), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 2, 26), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 4, 28), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 6, 36) ... and 1 more)
+>strMem : Symbol(strMem, Decl(lateBoundElementAccessAssignmentDeclarations.ts, 4, 5))
+
+const z: string = foo[numMem];
+>z : Symbol(z, Decl(lateBoundElementAccessAssignmentDeclarations.ts, 13, 5))
+>foo : Symbol(foo, Decl(lateBoundElementAccessAssignmentDeclarations.ts, 0, 0), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 0, 24), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 2, 26), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 4, 28), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 6, 36) ... and 1 more)
+>numMem : Symbol(numMem, Decl(lateBoundElementAccessAssignmentDeclarations.ts, 8, 5))
+
+const a: string = foo[dashStrMem];
+>a : Symbol(a, Decl(lateBoundElementAccessAssignmentDeclarations.ts, 14, 5))
+>foo : Symbol(foo, Decl(lateBoundElementAccessAssignmentDeclarations.ts, 0, 0), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 0, 24), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 2, 26), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 4, 28), Decl(lateBoundElementAccessAssignmentDeclarations.ts, 6, 36) ... and 1 more)
+>dashStrMem : Symbol(dashStrMem, Decl(lateBoundElementAccessAssignmentDeclarations.ts, 6, 5))
+
diff --git a/tests/baselines/reference/lateBoundElementAccessAssignmentDeclarations.types b/tests/baselines/reference/lateBoundElementAccessAssignmentDeclarations.types
new file mode 100644
index 0000000000000..2175a04ecfc96
--- /dev/null
+++ b/tests/baselines/reference/lateBoundElementAccessAssignmentDeclarations.types
@@ -0,0 +1,80 @@
+=== tests/cases/compiler/lateBoundElementAccessAssignmentDeclarations.ts ===
+export function foo() {}
+>foo : typeof foo
+
+foo.bar = 12;
+>foo.bar = 12 : 12
+>foo.bar : number
+>foo : typeof foo
+>bar : number
+>12 : 12
+
+const _private = Symbol();
+>_private : unique symbol
+>Symbol() : unique symbol
+>Symbol : SymbolConstructor
+
+foo[_private] = "ok";
+>foo[_private] = "ok" : "ok"
+>foo[_private] : string
+>foo : typeof foo
+>_private : unique symbol
+>"ok" : "ok"
+
+const strMem = "strMemName";
+>strMem : "strMemName"
+>"strMemName" : "strMemName"
+
+foo[strMem] = "ok";
+>foo[strMem] = "ok" : "ok"
+>foo[strMem] : string
+>foo : typeof foo
+>strMem : "strMemName"
+>"ok" : "ok"
+
+const dashStrMem = "dashed-str-mem";
+>dashStrMem : "dashed-str-mem"
+>"dashed-str-mem" : "dashed-str-mem"
+
+foo[dashStrMem] = "ok";
+>foo[dashStrMem] = "ok" : "ok"
+>foo[dashStrMem] : string
+>foo : typeof foo
+>dashStrMem : "dashed-str-mem"
+>"ok" : "ok"
+
+const numMem = 42;
+>numMem : 42
+>42 : 42
+
+foo[numMem] = "ok";
+>foo[numMem] = "ok" : "ok"
+>foo[numMem] : string
+>foo : typeof foo
+>numMem : 42
+>"ok" : "ok"
+
+const x: string = foo[_private];
+>x : string
+>foo[_private] : string
+>foo : typeof foo
+>_private : unique symbol
+
+const y: string = foo[strMem];
+>y : string
+>foo[strMem] : string
+>foo : typeof foo
+>strMem : "strMemName"
+
+const z: string = foo[numMem];
+>z : string
+>foo[numMem] : string
+>foo : typeof foo
+>numMem : 42
+
+const a: string = foo[dashStrMem];
+>a : string
+>foo[dashStrMem] : string
+>foo : typeof foo
+>dashStrMem : "dashed-str-mem"
+
diff --git a/tests/baselines/reference/lateBoundElementAccessAssignmentDeclarationsInJs.js b/tests/baselines/reference/lateBoundElementAccessAssignmentDeclarationsInJs.js
new file mode 100644
index 0000000000000..a9b6a0a86cdfa
--- /dev/null
+++ b/tests/baselines/reference/lateBoundElementAccessAssignmentDeclarationsInJs.js
@@ -0,0 +1,29 @@
+//// [file.js]
+export function foo() {}
+foo.bar = 12;
+const _private = Symbol();
+foo[_private] = "ok";
+const strMem = "strMemName";
+foo[strMem] = "ok";
+const dashStrMem = "dashed-str-mem";
+foo[dashStrMem] = "ok";
+const numMem = 42;
+foo[numMem] = "ok";
+
+/** @type {string} */
+const x = foo[_private];
+/** @type {string} */
+const y = foo[strMem];
+/** @type {string} */
+const z = foo[numMem];
+/** @type {string} */
+const a = foo[dashStrMem];
+
+
+
+//// [file.d.ts]
+export function foo(): void;
+export namespace foo {
+    export const bar: number;
+    export const strMemName: string;
+}
diff --git a/tests/baselines/reference/lateBoundElementAccessAssignmentDeclarationsInJs.symbols b/tests/baselines/reference/lateBoundElementAccessAssignmentDeclarationsInJs.symbols
new file mode 100644
index 0000000000000..669ed588b19b2
--- /dev/null
+++ b/tests/baselines/reference/lateBoundElementAccessAssignmentDeclarationsInJs.symbols
@@ -0,0 +1,62 @@
+=== tests/cases/compiler/file.js ===
+export function foo() {}
+>foo : Symbol(foo, Decl(file.js, 0, 0), Decl(file.js, 0, 24), Decl(file.js, 2, 26), Decl(file.js, 4, 28), Decl(file.js, 6, 36) ... and 1 more)
+
+foo.bar = 12;
+>foo.bar : Symbol(foo.bar, Decl(file.js, 0, 24))
+>foo : Symbol(foo, Decl(file.js, 0, 0), Decl(file.js, 0, 24), Decl(file.js, 2, 26), Decl(file.js, 4, 28), Decl(file.js, 6, 36) ... and 1 more)
+>bar : Symbol(foo.bar, Decl(file.js, 0, 24))
+
+const _private = Symbol();
+>_private : Symbol(_private, Decl(file.js, 2, 5))
+>Symbol : Symbol(Symbol, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.symbol.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --))
+
+foo[_private] = "ok";
+>foo : Symbol(foo, Decl(file.js, 0, 0), Decl(file.js, 0, 24), Decl(file.js, 2, 26), Decl(file.js, 4, 28), Decl(file.js, 6, 36) ... and 1 more)
+>_private : Symbol(_private, Decl(file.js, 2, 5))
+
+const strMem = "strMemName";
+>strMem : Symbol(strMem, Decl(file.js, 4, 5))
+
+foo[strMem] = "ok";
+>foo : Symbol(foo, Decl(file.js, 0, 0), Decl(file.js, 0, 24), Decl(file.js, 2, 26), Decl(file.js, 4, 28), Decl(file.js, 6, 36) ... and 1 more)
+>strMem : Symbol(strMem, Decl(file.js, 4, 5))
+
+const dashStrMem = "dashed-str-mem";
+>dashStrMem : Symbol(dashStrMem, Decl(file.js, 6, 5))
+
+foo[dashStrMem] = "ok";
+>foo : Symbol(foo, Decl(file.js, 0, 0), Decl(file.js, 0, 24), Decl(file.js, 2, 26), Decl(file.js, 4, 28), Decl(file.js, 6, 36) ... and 1 more)
+>dashStrMem : Symbol(dashStrMem, Decl(file.js, 6, 5))
+
+const numMem = 42;
+>numMem : Symbol(numMem, Decl(file.js, 8, 5))
+
+foo[numMem] = "ok";
+>foo : Symbol(foo, Decl(file.js, 0, 0), Decl(file.js, 0, 24), Decl(file.js, 2, 26), Decl(file.js, 4, 28), Decl(file.js, 6, 36) ... and 1 more)
+>numMem : Symbol(numMem, Decl(file.js, 8, 5))
+
+/** @type {string} */
+const x = foo[_private];
+>x : Symbol(x, Decl(file.js, 12, 5))
+>foo : Symbol(foo, Decl(file.js, 0, 0), Decl(file.js, 0, 24), Decl(file.js, 2, 26), Decl(file.js, 4, 28), Decl(file.js, 6, 36) ... and 1 more)
+>_private : Symbol(_private, Decl(file.js, 2, 5))
+
+/** @type {string} */
+const y = foo[strMem];
+>y : Symbol(y, Decl(file.js, 14, 5))
+>foo : Symbol(foo, Decl(file.js, 0, 0), Decl(file.js, 0, 24), Decl(file.js, 2, 26), Decl(file.js, 4, 28), Decl(file.js, 6, 36) ... and 1 more)
+>strMem : Symbol(strMem, Decl(file.js, 4, 5))
+
+/** @type {string} */
+const z = foo[numMem];
+>z : Symbol(z, Decl(file.js, 16, 5))
+>foo : Symbol(foo, Decl(file.js, 0, 0), Decl(file.js, 0, 24), Decl(file.js, 2, 26), Decl(file.js, 4, 28), Decl(file.js, 6, 36) ... and 1 more)
+>numMem : Symbol(numMem, Decl(file.js, 8, 5))
+
+/** @type {string} */
+const a = foo[dashStrMem];
+>a : Symbol(a, Decl(file.js, 18, 5))
+>foo : Symbol(foo, Decl(file.js, 0, 0), Decl(file.js, 0, 24), Decl(file.js, 2, 26), Decl(file.js, 4, 28), Decl(file.js, 6, 36) ... and 1 more)
+>dashStrMem : Symbol(dashStrMem, Decl(file.js, 6, 5))
+
diff --git a/tests/baselines/reference/lateBoundElementAccessAssignmentDeclarationsInJs.types b/tests/baselines/reference/lateBoundElementAccessAssignmentDeclarationsInJs.types
new file mode 100644
index 0000000000000..d2c80bf4a5897
--- /dev/null
+++ b/tests/baselines/reference/lateBoundElementAccessAssignmentDeclarationsInJs.types
@@ -0,0 +1,84 @@
+=== tests/cases/compiler/file.js ===
+export function foo() {}
+>foo : typeof foo
+
+foo.bar = 12;
+>foo.bar = 12 : 12
+>foo.bar : number
+>foo : typeof foo
+>bar : number
+>12 : 12
+
+const _private = Symbol();
+>_private : unique symbol
+>Symbol() : unique symbol
+>Symbol : SymbolConstructor
+
+foo[_private] = "ok";
+>foo[_private] = "ok" : "ok"
+>foo[_private] : string
+>foo : typeof foo
+>_private : unique symbol
+>"ok" : "ok"
+
+const strMem = "strMemName";
+>strMem : "strMemName"
+>"strMemName" : "strMemName"
+
+foo[strMem] = "ok";
+>foo[strMem] = "ok" : "ok"
+>foo[strMem] : string
+>foo : typeof foo
+>strMem : "strMemName"
+>"ok" : "ok"
+
+const dashStrMem = "dashed-str-mem";
+>dashStrMem : "dashed-str-mem"
+>"dashed-str-mem" : "dashed-str-mem"
+
+foo[dashStrMem] = "ok";
+>foo[dashStrMem] = "ok" : "ok"
+>foo[dashStrMem] : string
+>foo : typeof foo
+>dashStrMem : "dashed-str-mem"
+>"ok" : "ok"
+
+const numMem = 42;
+>numMem : 42
+>42 : 42
+
+foo[numMem] = "ok";
+>foo[numMem] = "ok" : "ok"
+>foo[numMem] : string
+>foo : typeof foo
+>numMem : 42
+>"ok" : "ok"
+
+/** @type {string} */
+const x = foo[_private];
+>x : string
+>foo[_private] : string
+>foo : typeof foo
+>_private : unique symbol
+
+/** @type {string} */
+const y = foo[strMem];
+>y : string
+>foo[strMem] : string
+>foo : typeof foo
+>strMem : "strMemName"
+
+/** @type {string} */
+const z = foo[numMem];
+>z : string
+>foo[numMem] : string
+>foo : typeof foo
+>numMem : 42
+
+/** @type {string} */
+const a = foo[dashStrMem];
+>a : string
+>foo[dashStrMem] : string
+>foo : typeof foo
+>dashStrMem : "dashed-str-mem"
+
diff --git a/tests/cases/compiler/lateBoundElementAccessAssignmentDeclarations.ts b/tests/cases/compiler/lateBoundElementAccessAssignmentDeclarations.ts
new file mode 100644
index 0000000000000..fc90e9486bb6c
--- /dev/null
+++ b/tests/cases/compiler/lateBoundElementAccessAssignmentDeclarations.ts
@@ -0,0 +1,18 @@
+// @strict: true
+// @declaration: true
+// @target: es6
+export function foo() {}
+foo.bar = 12;
+const _private = Symbol();
+foo[_private] = "ok";
+const strMem = "strMemName";
+foo[strMem] = "ok";
+const dashStrMem = "dashed-str-mem";
+foo[dashStrMem] = "ok";
+const numMem = 42;
+foo[numMem] = "ok";
+
+const x: string = foo[_private];
+const y: string = foo[strMem];
+const z: string = foo[numMem];
+const a: string = foo[dashStrMem];
\ No newline at end of file
diff --git a/tests/cases/compiler/lateBoundElementAccessAssignmentDeclarationsInJs.ts b/tests/cases/compiler/lateBoundElementAccessAssignmentDeclarationsInJs.ts
new file mode 100644
index 0000000000000..878d05ffa0a5a
--- /dev/null
+++ b/tests/cases/compiler/lateBoundElementAccessAssignmentDeclarationsInJs.ts
@@ -0,0 +1,26 @@
+// @strict: true
+// @declaration: true
+// @target: es6
+// @checkJs: true
+// @allowJs: true
+// @emitDeclarationOnly: true
+// @filename: file.js
+export function foo() {}
+foo.bar = 12;
+const _private = Symbol();
+foo[_private] = "ok";
+const strMem = "strMemName";
+foo[strMem] = "ok";
+const dashStrMem = "dashed-str-mem";
+foo[dashStrMem] = "ok";
+const numMem = 42;
+foo[numMem] = "ok";
+
+/** @type {string} */
+const x = foo[_private];
+/** @type {string} */
+const y = foo[strMem];
+/** @type {string} */
+const z = foo[numMem];
+/** @type {string} */
+const a = foo[dashStrMem];
\ No newline at end of file