diff --git a/src/main/java/com/google/devtools/build/lib/syntax/BuildFileAST.java b/src/main/java/com/google/devtools/build/lib/syntax/BuildFileAST.java
index 98ab055..497715a 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/BuildFileAST.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/BuildFileAST.java
@@ -253,12 +253,12 @@
   public static BuildFileAST parseBuildFile(ParserInputSource input,
                                             List<Statement> preludeStatements,
                                             EventHandler eventHandler) {
-    Parser.ParseResult result = Parser.parseFile(input, eventHandler, false);
+    Parser.ParseResult result = Parser.parseFile(input, eventHandler);
     return create(preludeStatements, result, /*contentHashCode=*/ null, eventHandler);
   }
 
   public static BuildFileAST parseBuildFile(ParserInputSource input, EventHandler eventHandler) {
-    Parser.ParseResult result = Parser.parseFile(input, eventHandler, false);
+    Parser.ParseResult result = Parser.parseFile(input, eventHandler);
     return create(ImmutableList.<Statement>of(), result, /*contentHashCode=*/ null, eventHandler);
   }
 
@@ -322,7 +322,7 @@
   public static BuildFileAST parseBuildString(EventHandler eventHandler, String... content) {
     String str = Joiner.on("\n").join(content);
     ParserInputSource input = ParserInputSource.create(str, null);
-    Parser.ParseResult result = Parser.parseFile(input, eventHandler, false);
+    Parser.ParseResult result = Parser.parseFile(input, eventHandler);
     return create(ImmutableList.<Statement>of(), result, null, eventHandler);
   }
 
@@ -339,9 +339,8 @@
    *
    * @return true if the input file is syntactically valid
    */
-  public static boolean checkSyntax(
-      ParserInputSource input, EventHandler eventHandler, boolean parsePython) {
-    Parser.ParseResult result = Parser.parseFile(input, eventHandler, parsePython);
+  public static boolean checkSyntax(ParserInputSource input, EventHandler eventHandler) {
+    Parser.ParseResult result = Parser.parseFile(input, eventHandler);
     return !result.containsErrors;
   }
 
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/Environment.java b/src/main/java/com/google/devtools/build/lib/syntax/Environment.java
index 177c052..a1dd6ea 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/Environment.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/Environment.java
@@ -934,7 +934,7 @@
       valid.validateAst(result.statements, eventHandler);
       statements = result.statements;
     } else {
-      statements = Parser.parseFile(input, eventHandler, /*parsePython=*/false).statements;
+      statements = Parser.parseFile(input, eventHandler).statements;
     }
     // Force the validation of imports
     BuildFileAST.fetchLoads(statements, eventHandler);
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/Lexer.java b/src/main/java/com/google/devtools/build/lib/syntax/Lexer.java
index 4c923d0..d8b34be 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/Lexer.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/Lexer.java
@@ -91,19 +91,16 @@
 
   private boolean containsErrors;
 
-  private boolean parsePython;
-
   /**
-   * Constructs a lexer which tokenizes the contents of the specified
-   * InputBuffer. Any errors during lexing are reported on "handler".
+   * Constructs a lexer which tokenizes the contents of the specified InputBuffer. Any errors during
+   * lexing are reported on "handler".
    */
-  public Lexer(ParserInputSource input, EventHandler eventHandler, boolean parsePython,
-      LineNumberTable lineNumberTable) {
+  public Lexer(
+      ParserInputSource input, EventHandler eventHandler, LineNumberTable lineNumberTable) {
     this.buffer = input.getContent();
     // Empirical measurements show roughly 1 token per 8 characters in buffer.
     this.tokens = Lists.newArrayListWithExpectedSize(buffer.length / 8);
     this.pos = 0;
-    this.parsePython = parsePython;
     this.eventHandler = eventHandler;
     this.locationInfo = new LocationInfo(input.getPath(), lineNumberTable);
 
@@ -114,13 +111,7 @@
   }
 
   public Lexer(ParserInputSource input, EventHandler eventHandler) {
-    this(input, eventHandler, /*parsePython=*/false,
-        LineNumberTable.create(input.getContent(), input.getPath()));
-  }
-
-  public Lexer(ParserInputSource input, EventHandler eventHandler, boolean parsePython) {
-    this(input, eventHandler, parsePython,
-        LineNumberTable.create(input.getContent(), input.getPath()));
+    this(input, eventHandler, LineNumberTable.create(input.getContent(), input.getPath()));
   }
 
   /**
@@ -822,12 +813,7 @@
         } else if (Character.isJavaIdentifierStart(c) && c != '$') {
           addToken(identifierOrKeyword());
         } else {
-          // Some characters in Python are not recognized in Blaze syntax (e.g. '!')
-          if (parsePython) {
-            addToken(new Token(TokenKind.ILLEGAL, pos - 1, pos, Character.toString(c)));
-          } else {
-            error("invalid character: '" + c + "'");
-          }
+          error("invalid character: '" + c + "'");
         }
         break;
       } // default
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/Parser.java b/src/main/java/com/google/devtools/build/lib/syntax/Parser.java
index ffe9f02..73da09b 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/Parser.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/Parser.java
@@ -15,7 +15,6 @@
 package com.google.devtools.build.lib.syntax;
 
 import static com.google.devtools.build.lib.syntax.Parser.ParsingMode.BUILD;
-import static com.google.devtools.build.lib.syntax.Parser.ParsingMode.PYTHON;
 import static com.google.devtools.build.lib.syntax.Parser.ParsingMode.SKYLARK;
 
 import com.google.common.annotations.VisibleForTesting;
@@ -82,8 +81,6 @@
     BUILD,
     /** Used for parsing .bzl files */
     SKYLARK,
-    /** Used for syntax checking, ignoring all Python blocks (e.g. def, class, try) */
-    PYTHON,
   }
 
   private static final EnumSet<TokenKind> STATEMENT_TERMINATOR_SET =
@@ -212,14 +209,12 @@
   }
 
   /**
-   * Entry-point to parser that parses a build file with comments.  All errors
-   * encountered during parsing are reported via "reporter".
+   * Entry-point to parser that parses a build file with comments. All errors encountered during
+   * parsing are reported via "reporter".
    */
-  public static ParseResult parseFile(
-      ParserInputSource input, EventHandler eventHandler, boolean parsePython) {
-    Lexer lexer = new Lexer(input, eventHandler, parsePython);
-    ParsingMode parsingMode = parsePython ? PYTHON : BUILD;
-    Parser parser = new Parser(lexer, eventHandler, parsingMode);
+  public static ParseResult parseFile(ParserInputSource input, EventHandler eventHandler) {
+    Lexer lexer = new Lexer(input, eventHandler);
+    Parser parser = new Parser(lexer, eventHandler, BUILD);
     List<Statement> statements = parser.parseFileInput();
     return new ParseResult(statements, parser.comments, locationFromStatements(lexer, statements),
         parser.errorsCount > 0 || lexer.containsErrors());
@@ -232,7 +227,7 @@
    */
   public static ParseResult parseFileForSkylark(
       ParserInputSource input, EventHandler eventHandler) {
-    Lexer lexer = new Lexer(input, eventHandler, false);
+    Lexer lexer = new Lexer(input, eventHandler);
     Parser parser = new Parser(lexer, eventHandler, SKYLARK);
     List<Statement> statements = parser.parseFileInput();
     return new ParseResult(
@@ -249,7 +244,7 @@
    */
   @VisibleForTesting
   public static Expression parseExpression(ParserInputSource input, EventHandler eventHandler) {
-    Lexer lexer = new Lexer(input, eventHandler, false);
+    Lexer lexer = new Lexer(input, eventHandler);
     Parser parser = new Parser(lexer, eventHandler, null);
     Expression result = parser.parseExpression();
     while (parser.token.kind == TokenKind.NEWLINE) {
@@ -345,7 +340,7 @@
           TokenKind.TRY, TokenKind.WITH, TokenKind.WHILE, TokenKind.YIELD);
 
   private void checkForbiddenKeywords(Token token) {
-    if (parsingMode == PYTHON || !FORBIDDEN_KEYWORDS.contains(token.kind)) {
+    if (!FORBIDDEN_KEYWORDS.contains(token.kind)) {
       return;
     }
     String error;
@@ -1435,7 +1430,7 @@
       reportError(
           lexer.createLocation(blockToken.left, blockToken.right),
           "syntax error at 'else': not allowed here.");
-    } else if (parsingMode != PYTHON) {
+    } else {
       String msg =
           ILLEGAL_BLOCK_KEYWORDS.containsKey(blockToken.kind)
               ? String.format("%ss are not supported.", ILLEGAL_BLOCK_KEYWORDS.get(blockToken.kind))
diff --git a/src/test/java/com/google/devtools/build/lib/syntax/ParserTest.java b/src/test/java/com/google/devtools/build/lib/syntax/ParserTest.java
index e4d8e3b..36ecfe1 100644
--- a/src/test/java/com/google/devtools/build/lib/syntax/ParserTest.java
+++ b/src/test/java/com/google/devtools/build/lib/syntax/ParserTest.java
@@ -20,7 +20,6 @@
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 
-import com.google.common.base.Joiner;
 import com.google.common.collect.ImmutableList;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.events.Location;
@@ -58,14 +57,6 @@
     return parseFileWithComments(input).getStatements();
   }
 
-  /** Parses a build code (not Skylark) with PythonProcessing enabled */
-  private List<Statement> parseFileWithPython(String... input) {
-    return Parser.parseFile(
-        ParserInputSource.create(Joiner.on("\n").join(input), null),
-        getEventHandler(),
-        /*parsePython=*/true).statements;
-  }
-
   /** Parses Skylark code */
   private List<Statement> parseFileForSkylark(String... input) {
     return env.parseFile(input);
@@ -902,64 +893,6 @@
   }
 
   @Test
-  public void testFunctionDefinitionIgnoredEvenWithUnsupportedKeyword() throws Exception {
-    // Parser skips over entire function definitions without reporting error,
-    // when parsePython is set to true.
-    List<Statement> stmts = parseFileWithPython(
-        "x = 1;",
-        "def foo(x, y, **z):",
-        "  try:",
-        "    x = 2",
-        "  with: pass",
-        "  return 2",
-        "x = 3");
-    assertThat(stmts).hasSize(2);
-  }
-
-  @Test
-  public void testFunctionDefinitionIgnored() throws Exception {
-    // Parser skips over entire function definitions without reporting error,
-    // when parsePython is set to true.
-    List<Statement> stmts = parseFileWithPython(
-        "x = 1;",
-        "def foo(x, y, **z):",
-        "  # a comment",
-        "  if true:",
-        "    x = 2",
-        "  foo(bar)",
-        "  return z",
-        "x = 3");
-    assertThat(stmts).hasSize(2);
-
-    stmts = parseFileWithPython(
-        "x = 1;",
-        "def foo(x, y, **z): return x",
-        "x = 3");
-    assertThat(stmts).hasSize(2);
-  }
-
-  @Test
-  public void testMissingBlock() throws Exception {
-    setFailFast(false);
-    List<Statement> stmts = parseFileWithPython(
-        "x = 1;",
-        "def foo(x):",
-        "x = 2;\n");
-    assertThat(stmts).hasSize(2);
-    assertContainsError("expected an indented block");
-  }
-
-  @Test
-  public void testInvalidDef() throws Exception {
-    setFailFast(false);
-    parseFileWithPython(
-        "x = 1;",
-        "def foo(x)",
-        "x = 2;\n");
-    assertContainsError("syntax error at 'EOF'");
-  }
-
-  @Test
   public void testDefSingleLine() throws Exception {
     List<Statement> statements = parseFileForSkylark(
         "def foo(): x = 1; y = 2\n");
@@ -968,19 +901,6 @@
   }
 
   @Test
-  public void testSkipIfBlock() throws Exception {
-    // Skip over 'if' blocks, when parsePython is set
-    List<Statement> stmts = parseFileWithPython(
-        "x = 1;",
-        "if x == 1:",
-        "  foo(x)",
-        "else:",
-        "  bar(x)",
-        "x = 3;\n");
-    assertThat(stmts).hasSize(2);
-  }
-
-  @Test
   public void testPass() throws Exception {
     List<Statement> statements = parseFileForSkylark("pass\n");
     assertThat(statements).isEmpty();