diff --git a/spec/text-editor-spec.js b/spec/text-editor-spec.js
index 72e1e9f53..3afcce5ce 100644
--- a/spec/text-editor-spec.js
+++ b/spec/text-editor-spec.js
@@ -85,22 +85,6 @@ describe('TextEditor', () => {
     })
   })
 
-  describe('when the editor is constructed with the largeFileMode option set to true', () => {
-    it("loads the editor but doesn't tokenize", async () => {
-      editor = await atom.workspace.openTextFile('sample.js', {largeFileMode: true})
-      buffer = editor.getBuffer()
-      expect(editor.lineTextForScreenRow(0)).toBe(buffer.lineForRow(0))
-      expect(editor.tokensForScreenRow(0).length).toBe(1)
-      expect(editor.tokensForScreenRow(1).length).toBe(2) // soft tab
-      expect(editor.lineTextForScreenRow(12)).toBe(buffer.lineForRow(12))
-      expect(editor.getCursorScreenPosition()).toEqual([0, 0])
-
-      editor.insertText('hey"')
-      expect(editor.tokensForScreenRow(0).length).toBe(1)
-      expect(editor.tokensForScreenRow(1).length).toBe(2)
-    })
-  })
-
   describe('.copy()', () => {
     it('returns a different editor with the same initial state', () => {
       expect(editor.getAutoHeight()).toBeFalsy()
diff --git a/spec/tokenized-buffer-spec.js b/spec/tokenized-buffer-spec.js
index b1574673a..8bc55d538 100644
--- a/spec/tokenized-buffer-spec.js
+++ b/spec/tokenized-buffer-spec.js
@@ -33,6 +33,34 @@ describe('TokenizedBuffer', () => {
     }
   }
 
+  describe('when the editor is constructed with the largeFileMode option set to true', () => {
+    it("loads the editor but doesn't tokenize", async () => {
+      const line = 'a b c d\n'
+      buffer = new TextBuffer(line.repeat(256 * 1024))
+      expect(buffer.getText().length).toBe(2 * 1024 * 1024)
+      tokenizedBuffer = new TokenizedBuffer({
+        buffer,
+        grammar: atom.grammars.grammarForScopeName('source.js'),
+        tabLength: 2
+      })
+      buffer.setLanguageMode(tokenizedBuffer)
+
+      expect(tokenizedBuffer.isRowCommented(0)).toBeFalsy()
+
+      // It treats the entire line as one big token
+      let iterator = tokenizedBuffer.buildHighlightIterator()
+      iterator.seek({row: 0, column: 0})
+      iterator.moveToSuccessor()
+      expect(iterator.getPosition()).toEqual({row: 0, column: 7})
+
+      buffer.insert([0, 0], 'hey"')
+      iterator = tokenizedBuffer.buildHighlightIterator()
+      iterator.seek({row: 0, column: 0})
+      iterator.moveToSuccessor()
+      expect(iterator.getPosition()).toEqual({row: 0, column: 11})
+    })
+  })
+
   describe('serialization', () => {
     describe('when the underlying buffer has a path', () => {
       beforeEach(async () => {
diff --git a/src/text-editor.js b/src/text-editor.js
index b98461b28..ac495a355 100644
--- a/src/text-editor.js
+++ b/src/text-editor.js
@@ -123,7 +123,6 @@ class TextEditor {
     this.mini = (params.mini != null) ? params.mini : false
     this.placeholderText = params.placeholderText
     this.showLineNumbers = params.showLineNumbers
-    this.largeFileMode = params.largeFileMode
     this.assert = params.assert || (condition => condition)
     this.showInvisibles = (params.showInvisibles != null) ? params.showInvisibles : true
     this.autoHeight = params.autoHeight
@@ -528,7 +527,6 @@ class TextEditor {
       mini: this.mini,
       editorWidthInChars: this.editorWidthInChars,
       width: this.width,
-      largeFileMode: this.largeFileMode,
       maxScreenLineLength: this.maxScreenLineLength,
       registered: this.registered,
       invisibles: this.invisibles,
diff --git a/src/tokenized-buffer.js b/src/tokenized-buffer.js
index 0ddbebdf1..633187198 100644
--- a/src/tokenized-buffer.js
+++ b/src/tokenized-buffer.js
@@ -29,6 +29,9 @@ class TokenizedBuffer {
     this.tabLength = params.tabLength
     this.largeFileMode = params.largeFileMode
     this.config = params.config
+    this.largeFileMode = params.largeFileMode != null
+      ? params.largeFileMode
+      : this.buffer.buffer.getLength() >= 2 * 1024 * 1024
 
     this.grammar = params.grammar || NullGrammar
     this.rootScopeDescriptor = new ScopeDescriptor({scopes: [this.grammar.scopeName]})
diff --git a/src/workspace.js b/src/workspace.js
index 3e47a8fad..9f2ad397b 100644
--- a/src/workspace.js
+++ b/src/workspace.js
@@ -1211,9 +1211,7 @@ module.exports = class Workspace extends Model {
     }
 
     const fileSize = fs.getSizeSync(filePath)
-
-    const largeFileMode = fileSize >= (2 * 1048576) // 2MB
-    if (fileSize >= (this.config.get('core.warnOnLargeFileLimit') * 1048576)) { // 20MB by default
+    if (fileSize >= (this.config.get('core.warnOnLargeFileLimit') * 1048576)) {
       const choice = this.applicationDelegate.confirm({
         message: 'Atom will be unresponsive during the loading of very large files.',
         detailedMessage: 'Do you still want to load this file?',
@@ -1228,7 +1226,7 @@ module.exports = class Workspace extends Model {
 
     return this.project.bufferForPath(filePath, options)
       .then(buffer => {
-        return this.textEditorRegistry.build(Object.assign({buffer, largeFileMode, autoHeight: false}, options))
+        return this.textEditorRegistry.build(Object.assign({buffer, autoHeight: false}, options))
       })
   }