diff --git a/src/compiler/binder.ts b/src/compiler/binder.ts
index b3554876c14..5f7771d02ea 100644
--- a/src/compiler/binder.ts
+++ b/src/compiler/binder.ts
@@ -2163,6 +2163,8 @@ namespace ts {
                     return bindJsxAttribute(<JsxAttribute>node, SymbolFlags.Property, SymbolFlags.PropertyExcludes);
 
                 // Imports and exports
+                case SyntaxKind.ImportCallExpression:
+                    return bindImportCallExpression(<ImportCallExpression>node);
                 case SyntaxKind.ImportEqualsDeclaration:
                 case SyntaxKind.NamespaceImport:
                 case SyntaxKind.ImportSpecifier:
@@ -2267,6 +2269,15 @@ namespace ts {
             }
         }
 
+        function bindImportCallExpression(node: ImportCallExpression) {
+            if (!file.dynamicImportIndicator) {
+                file.dynamicImportIndicator = node;
+                if (!file.externalModuleIndicator) {
+                    bindSourceFileAsExternalModule();
+                }
+            }
+        }
+
         function bindImportClause(node: ImportClause) {
             if (node.name) {
                 declareSymbolAndAddToSymbolTable(node, SymbolFlags.Alias, SymbolFlags.AliasExcludes);
diff --git a/src/compiler/factory.ts b/src/compiler/factory.ts
index 0bd7989327b..962bbc7e234 100644
--- a/src/compiler/factory.ts
+++ b/src/compiler/factory.ts
@@ -1644,7 +1644,7 @@ namespace ts {
             if (node.resolvedTypeReferenceDirectiveNames !== undefined) updated.resolvedTypeReferenceDirectiveNames = node.resolvedTypeReferenceDirectiveNames;
             if (node.imports !== undefined) updated.imports = node.imports;
             if (node.moduleAugmentations !== undefined) updated.moduleAugmentations = node.moduleAugmentations;
-            if (node.containsDynamicImport !== undefined) updated.containsDynamicImport = node.containsDynamicImport;
+            if (node.dynamicImportIndicator !== undefined) updated.dynamicImportIndicator = node.dynamicImportIndicator;
             return updateNode(updated, node);
         }
 
diff --git a/src/compiler/parser.ts b/src/compiler/parser.ts
index a7427e58134..e4931b09e3c 100644
--- a/src/compiler/parser.ts
+++ b/src/compiler/parser.ts
@@ -461,7 +461,11 @@ namespace ts {
     }
 
     export function isExternalModule(file: SourceFile): boolean {
-        return file.externalModuleIndicator !== undefined || file.containsDynamicImport;
+        return file.externalModuleIndicator !== undefined;
+    }
+
+    export function containedDynamicImport(file: SourceFile): boolean {
+        return file.dynamicImportIndicator !== undefined;
     }
 
     // Produces a new SourceFile for the 'newText' provided. The 'textChangeRange' parameter
diff --git a/src/compiler/transformers/module/module.ts b/src/compiler/transformers/module/module.ts
index 9d811243718..6614f1a063e 100644
--- a/src/compiler/transformers/module/module.ts
+++ b/src/compiler/transformers/module/module.ts
@@ -55,7 +55,7 @@ namespace ts {
          * @param node The SourceFile node.
          */
         function transformSourceFile(node: SourceFile) {
-            if (isDeclarationFile(node) || !(isExternalModule(node) || compilerOptions.isolatedModules)) {
+            if (isDeclarationFile(node) || !(isExternalModule(node) || compilerOptions.isolatedModules || containedDynamicImport(node))) {
                 return node;
             }
 
diff --git a/src/compiler/transformers/module/system.ts b/src/compiler/transformers/module/system.ts
index 2798c7ca2cc..32005722e63 100644
--- a/src/compiler/transformers/module/system.ts
+++ b/src/compiler/transformers/module/system.ts
@@ -50,9 +50,7 @@ namespace ts {
          * @param node The SourceFile node.
          */
         function transformSourceFile(node: SourceFile) {
-            if (isDeclarationFile(node)
-                || !(isExternalModule(node)
-                    || compilerOptions.isolatedModules)) {
+            if (isDeclarationFile(node) || !(isExternalModule(node) || compilerOptions.isolatedModules || containedDynamicImport(node))) {
                 return node;
             }
 
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index 07a6610f8fd..21da99c62ef 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -2253,6 +2253,7 @@ namespace ts {
         /* @internal */ externalModuleIndicator: Node;
         // The first node that causes this file to be a CommonJS module
         /* @internal */ commonJsModuleIndicator: Node;
+        /* @internal */ dynamicImportIndicator: Node;
 
         /* @internal */ identifiers: Map<string>;
         /* @internal */ nodeCount: number;
@@ -2282,7 +2283,6 @@ namespace ts {
         /* @internal */ moduleAugmentations: LiteralExpression[];
         /* @internal */ patternAmbientModules?: PatternAmbientModule[];
         /* @internal */ ambientModuleNames: string[];
-        /* @internal */ containsDynamicImport?: boolean;
     }
 
     export interface Bundle extends Node {
diff --git a/src/services/services.ts b/src/services/services.ts
index df5330ebaed..b0dd1f2eb1e 100644
--- a/src/services/services.ts
+++ b/src/services/services.ts
@@ -458,6 +458,7 @@ namespace ts {
         public hasNoDefaultLib: boolean;
         public externalModuleIndicator: Node; // The first node that causes this file to be an external module
         public commonJsModuleIndicator: Node; // The first node that causes this file to be a CommonJS module
+        public dynamicImportIndicator: Node; // The first dynamic import in this file
         public nodeCount: number;
         public identifierCount: number;
         public symbolCount: number;