diff --git a/docs/reference.md b/docs/reference.md
index 5a509df..75b75a0 100644
--- a/docs/reference.md
+++ b/docs/reference.md
@@ -699,7 +699,7 @@
       Shows defines set for the //base:base target, annotated by where
       each one was set from.
 ```
-### <a name="cmd_format"></a>**gn format [\--dump-tree] (\--stdin | &lt;list of build_files...&gt;)**&nbsp;[Back to Top](#gn-reference)
+### <a name="cmd_format"></a>**gn format [\--dump-tree] [\--format-width=WIDTH] (\--stdin | &lt;list of build_files...&gt;)**&nbsp;[Back to Top](#gn-reference)
 
 ```
   Formats .gn file to a standard format.
@@ -725,6 +725,10 @@
       - Exit code 1: general failure (parse error, etc.)
       - Exit code 2: successful format, but differs from on disk.
 
+  --format-width=WIDTH
+      Override the default format width. WIDTH must be a strictly positive
+      integer.
+
   --dump-tree[=( text | json )]
       Dumps the parse tree to stdout and does not update the file or print
       formatted output. If no format is specified, text format will be used.
@@ -8589,6 +8593,7 @@
     *   --enumerate-files-with-git: Use git to list files.
     *   --error-limit: Limit the number of errors or warnings to print.
     *   --fail-on-unused-args: Treat unused build args as fatal errors.
+    *   --format-width: Set the formatting width (default is 80)
     *   --markdown: Write help output in the Markdown format.
     *   --ninja-executable: Set the Ninja executable.
     *   --nocolor: Force non-colored output.
diff --git a/src/gn/command_format.cc b/src/gn/command_format.cc
index f7649cd..b49c480 100644
--- a/src/gn/command_format.cc
+++ b/src/gn/command_format.cc
@@ -12,6 +12,7 @@
 #include "base/files/file_util.h"
 #include "base/json/json_reader.h"
 #include "base/json/json_writer.h"
+#include "base/strings/string_number_conversions.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "gn/commands.h"
@@ -33,6 +34,8 @@
 
 namespace commands {
 
+const size_t kDefaultFormatWidth = 80;
+
 const char kSwitchDryRun[] = "dry-run";
 const char kSwitchDumpTree[] = "dump-tree";
 const char kSwitchReadTree[] = "read-tree";
@@ -43,7 +46,7 @@
 const char kFormat[] = "format";
 const char kFormat_HelpShort[] = "format: Format .gn files.";
 const char kFormat_Help[] =
-    R"(gn format [--dump-tree] (--stdin | <list of build_files...>)
+    R"(gn format [--dump-tree] [--format-width=WIDTH] (--stdin | <list of build_files...>)
 
   Formats .gn file to a standard format.
 
@@ -66,6 +69,10 @@
       - Exit code 1: general failure (parse error, etc.)
       - Exit code 2: successful format, but differs from on disk.
 
+  --format-width=WIDTH
+      Override the default format width. WIDTH must be a strictly positive
+      integer.
+
   --dump-tree[=( text | json )]
       Dumps the parse tree to stdout and does not update the file or print
       formatted output. If no format is specified, text format will be used.
@@ -91,7 +98,6 @@
 namespace {
 
 const int kIndentSize = 2;
-const int kMaximumWidth = 80;
 
 const int kPenaltyLineBreak = 500;
 const int kPenaltyHorizontalSeparation = 100;
@@ -130,7 +136,7 @@
 
 class Printer {
  public:
-  Printer();
+  Printer(size_t format_width);
   ~Printer();
 
   void Block(const ParseNode* file);
@@ -247,11 +253,12 @@
   bool ListWillBeMultiline(const std::vector<std::unique_ptr<PARSENODE>>& list,
                            const ParseNode* end);
 
+  size_t format_width_ = kDefaultFormatWidth;
   std::string output_;           // Output buffer.
   std::vector<Token> comments_;  // Pending end-of-line comments.
   int margin() const { return stack_.back().margin; }
 
-  int penalty_depth_;
+  int penalty_depth_ = 0;
   int GetPenaltyForLineBreak() const {
     return penalty_depth_ * kPenaltyLineBreak;
   }
@@ -285,7 +292,7 @@
   Printer& operator=(const Printer&) = delete;
 };
 
-Printer::Printer() : penalty_depth_(0) {
+Printer::Printer(size_t format_width) : format_width_(format_width) {
   output_.reserve(100 << 10);
   precedence_["="] = kPrecedenceAssign;
   precedence_["+="] = kPrecedenceAssign;
@@ -402,7 +409,7 @@
                           is_indented || has_url || is_list || is_pragma;
       paragraphs.push_back(p);
     } else {
-      if (margin() + trimmed.size() > kMaximumWidth) {
+      if (margin() + trimmed.size() > format_width_) {
         current_paragraph.should_reflow = true;
       }
       current_paragraph.tokens.push_back(c);
@@ -455,7 +462,7 @@
         }
 
         if (!have_empty_line && j < words.size() - 1 &&
-            CurrentColumn() + 1 + words[j + 1].size() > kMaximumWidth) {
+            CurrentColumn() + 1 + words[j + 1].size() > format_width_) {
           start_next_line();
           continuation = true;
         }
@@ -862,8 +869,8 @@
       output, "\n", base::KEEP_WHITESPACE, base::SPLIT_WANT_ALL);
   penalty += static_cast<int>(lines.size() - 1) * GetPenaltyForLineBreak();
   for (const auto& line : lines) {
-    if (line.size() > kMaximumWidth)
-      penalty += static_cast<int>(line.size() - kMaximumWidth) * kPenaltyExcess;
+    if (line.size() > format_width_)
+      penalty += static_cast<int>(line.size() - format_width_) * kPenaltyExcess;
   }
   return penalty;
 }
@@ -873,7 +880,7 @@
                                             base::SPLIT_WANT_ALL)) {
     std::string_view trimmed =
         TrimString(line, " ", base::TrimPositions::TRIM_TRAILING);
-    if (trimmed.size() > kMaximumWidth) {
+    if (trimmed.size() > format_width_) {
       return true;
     }
   }
@@ -980,7 +987,7 @@
     stack_.push_back(IndentState(indent_column,
                                  stack_.back().continuation_requires_indent,
                                  binop->op().value() == "||"));
-    Printer sub_left;
+    Printer sub_left(format_width_);
     InitializeSub(&sub_left);
     sub_left.Expr(binop->left(), prec_left,
                   std::string(" ") + std::string(binop->op().value()));
@@ -992,7 +999,7 @@
               std::back_inserter(comments_));
 
     // Single line.
-    Printer sub1;
+    Printer sub1(format_width_);
     InitializeSub(&sub1);
     sub1.Print(" ");
     int penalty_current_line = sub1.Expr(binop->right(), prec_right, at_end);
@@ -1007,7 +1014,7 @@
     }
 
     // Break after operator.
-    Printer sub2;
+    Printer sub2(format_width_);
     InitializeSub(&sub2);
     sub2.Newline();
     int penalty_next_line = sub2.Expr(binop->right(), prec_right, at_end);
@@ -1018,7 +1025,7 @@
     // Force a list on the RHS that would normally be a single line into
     // multiline.
     bool tried_rhs_multiline = false;
-    Printer sub3;
+    Printer sub3(format_width_);
     InitializeSub(&sub3);
     int penalty_multiline_rhs_list = std::numeric_limits<int>::max();
     const ListNode* rhs_list = binop->right()->AsList();
@@ -1238,7 +1245,7 @@
       list.size() != 1 || !list[0]->AsBinaryOp();
 
   // 1: Same line.
-  Printer sub1;
+  Printer sub1(format_width_);
   InitializeSub(&sub1);
   sub1.stack_.push_back(
       IndentState(CurrentColumn(), continuation_requires_indent, false));
@@ -1256,7 +1263,7 @@
       (CountLines(sub1.String()) - 1) * kPenaltyBrokenLineOnOneLiner;
 
   // 2: Starting on same line, broken at commas.
-  Printer sub2;
+  Printer sub2(format_width_);
   InitializeSub(&sub2);
   sub2.stack_.push_back(
       IndentState(CurrentColumn(), continuation_requires_indent, false));
@@ -1273,7 +1280,7 @@
   penalty_multiline_start_same_line += AssessPenalty(sub2.String());
 
   // 3: Starting on next line, broken at commas.
-  Printer sub3;
+  Printer sub3(format_width_);
   InitializeSub(&sub3);
   sub3.stack_.push_back(IndentState(margin() + kIndentSize * 2,
                                     continuation_requires_indent, false));
@@ -1402,6 +1409,7 @@
 
 void DoFormat(const ParseNode* root,
               TreeDumpMode dump_tree,
+              size_t format_width,
               std::string* output,
               std::string* dump_output) {
   if (dump_tree == TreeDumpMode::kPlainText) {
@@ -1415,23 +1423,26 @@
     *dump_output = os;
   }
 
-  Printer pr;
+  Printer pr(format_width);
   pr.Block(root);
   *output = pr.String();
 }
 
 }  // namespace
 
-bool FormatJsonToString(const std::string& json, std::string* output) {
+bool FormatJsonToString(const std::string& json,
+                        size_t format_width,
+                        std::string* output) {
   base::JSONReader reader;
   std::unique_ptr<base::Value> json_root = reader.Read(json);
   std::unique_ptr<ParseNode> root = ParseNode::BuildFromJSON(*json_root);
-  DoFormat(root.get(), TreeDumpMode::kInactive, output, nullptr);
+  DoFormat(root.get(), TreeDumpMode::kInactive, format_width, output, nullptr);
   return true;
 }
 
 bool FormatStringToString(const std::string& input,
                           TreeDumpMode dump_tree,
+                          size_t maximum_width,
                           std::string* output,
                           std::string* dump_output) {
   SourceFile source_file;
@@ -1453,7 +1464,7 @@
     return false;
   }
 
-  DoFormat(parse_node.get(), dump_tree, output, dump_output);
+  DoFormat(parse_node.get(), dump_tree, maximum_width, output, dump_output);
   return true;
 }
 
@@ -1464,13 +1475,12 @@
   _setmode(_fileno(stderr), _O_BINARY);
 #endif
 
-  bool dry_run =
-      base::CommandLine::ForCurrentProcess()->HasSwitch(kSwitchDryRun);
+  const base::CommandLine* cmdline = base::CommandLine::ForCurrentProcess();
+
+  bool dry_run = cmdline->HasSwitch(kSwitchDryRun);
   TreeDumpMode dump_tree = TreeDumpMode::kInactive;
-  if (base::CommandLine::ForCurrentProcess()->HasSwitch(kSwitchDumpTree)) {
-    std::string tree_type =
-        base::CommandLine::ForCurrentProcess()->GetSwitchValueString(
-            kSwitchDumpTree);
+  if (cmdline->HasSwitch(kSwitchDumpTree)) {
+    std::string tree_type = cmdline->GetSwitchValueString(kSwitchDumpTree);
     if (tree_type == kSwitchTreeTypeJSON) {
       dump_tree = TreeDumpMode::kJSON;
     } else if (tree_type.empty() || tree_type == kSwitchTreeTypeText) {
@@ -1485,16 +1495,29 @@
       return 1;
     }
   }
-  bool from_stdin =
-      base::CommandLine::ForCurrentProcess()->HasSwitch(kSwitchStdin);
+  bool from_stdin = cmdline->HasSwitch(kSwitchStdin);
 
   if (dry_run) {
     // --dry-run only works with an actual file to compare to.
     from_stdin = false;
   }
 
-  bool quiet =
-      base::CommandLine::ForCurrentProcess()->HasSwitch(switches::kQuiet);
+  bool quiet = cmdline->HasSwitch(switches::kQuiet);
+
+  size_t format_width = kDefaultFormatWidth;
+  if (cmdline->HasSwitch(switches::kFormatWidth)) {
+    const std::string format_width_str =
+        cmdline->GetSwitchValueString(switches::kFormatWidth);
+    int format_width_int = 0;
+    if (!base::StringToInt(
+            cmdline->GetSwitchValueString(switches::kFormatWidth),
+            &format_width_int) ||
+        format_width_int <= 0) {
+      Err(Location(), "Invalid --format-width value: " + format_width_str);
+      return 1;
+    }
+    format_width = static_cast<size_t>(format_width_int);
+  }
 
   if (from_stdin) {
     if (args.size() != 0) {
@@ -1502,10 +1525,13 @@
           .PrintToStdout();
       return 1;
     }
+
     std::string input = ReadStdin();
     std::string output;
     std::string dump_output;
-    if (!FormatStringToString(input, dump_tree, &output, &dump_output))
+
+    if (!FormatStringToString(input, dump_tree, format_width, &output,
+                              &dump_output))
       return 1;
     printf("%s", dump_output.c_str());
     printf("%s", output.c_str());
@@ -1522,10 +1548,8 @@
   SourceDir source_dir =
       SourceDirForCurrentDirectory(setup.build_settings().root_path());
 
-  if (base::CommandLine::ForCurrentProcess()->HasSwitch(kSwitchReadTree)) {
-    std::string tree_type =
-        base::CommandLine::ForCurrentProcess()->GetSwitchValueString(
-            kSwitchReadTree);
+  if (cmdline->HasSwitch(kSwitchReadTree)) {
+    std::string tree_type = cmdline->GetSwitchValueString(kSwitchReadTree);
     if (tree_type != kSwitchTreeTypeJSON) {
       Err(Location(), "Only json supported for read-tree.\n").PrintToStdout();
       return 1;
@@ -1546,7 +1570,7 @@
     }
     base::FilePath to_format = setup.build_settings().GetFullPath(file);
     std::string output;
-    FormatJsonToString(ReadStdin(), &output);
+    FormatJsonToString(ReadStdin(), format_width, &output);
     if (base::WriteFile(to_format, output.data(),
                         static_cast<int>(output.size())) == -1) {
       Err(Location(), std::string("Failed to write output to \"") +
@@ -1585,8 +1609,8 @@
 
     std::string output_string;
     std::string dump_output_string;
-    if (!FormatStringToString(original_contents, dump_tree, &output_string,
-                              &dump_output_string)) {
+    if (!FormatStringToString(original_contents, dump_tree, format_width,
+                              &output_string, &dump_output_string)) {
       exit_code = 1;
       continue;
     }
diff --git a/src/gn/command_format.h b/src/gn/command_format.h
index 0eb667f..7854d9e 100644
--- a/src/gn/command_format.h
+++ b/src/gn/command_format.h
@@ -24,10 +24,16 @@
   kJSON
 };
 
-bool FormatJsonToString(const std::string& input, std::string* output);
+// The default format width.
+extern const size_t kDefaultFormatWidth;
+
+bool FormatJsonToString(const std::string& input,
+                        size_t format_width,
+                        std::string* output);
 
 bool FormatStringToString(const std::string& input,
                           TreeDumpMode dump_tree,
+                          size_t format_width,
                           std::string* output,
                           std::string* dump_output);
 
diff --git a/src/gn/command_format_unittest.cc b/src/gn/command_format_unittest.cc
index 0149cbc..4a8c597 100644
--- a/src/gn/command_format_unittest.cc
+++ b/src/gn/command_format_unittest.cc
@@ -14,40 +14,46 @@
 
 using FormatTest = TestWithScheduler;
 
-#define FORMAT_TEST(n)                                                      \
-  TEST_F(FormatTest, n) {                                                   \
-    ::Setup setup;                                                          \
-    std::string input;                                                      \
-    std::string out;                                                        \
-    std::string expected;                                                   \
-    base::FilePath src_dir =                                                \
-        GetExePath().DirName().Append(FILE_PATH_LITERAL(".."));             \
-    base::SetCurrentDirectory(src_dir);                                     \
-    ASSERT_TRUE(base::ReadFileToString(                                     \
-        base::FilePath(FILE_PATH_LITERAL("src/gn/format_test_data/")        \
-                           FILE_PATH_LITERAL(#n) FILE_PATH_LITERAL(".gn")), \
-        &input));                                                           \
-    ASSERT_TRUE(base::ReadFileToString(                                     \
-        base::FilePath(FILE_PATH_LITERAL("src/gn/format_test_data/")        \
-                           FILE_PATH_LITERAL(#n)                            \
-                               FILE_PATH_LITERAL(".golden")),               \
-        &expected));                                                        \
-    EXPECT_TRUE(commands::FormatStringToString(                             \
-        input, commands::TreeDumpMode::kInactive, &out, nullptr));          \
-    EXPECT_EQ(expected, out);                                               \
-    /* Make sure formatting the output doesn't cause further changes. */    \
-    std::string out_again;                                                  \
-    EXPECT_TRUE(commands::FormatStringToString(                             \
-        out, commands::TreeDumpMode::kInactive, &out_again, nullptr));      \
-    ASSERT_EQ(out, out_again);                                              \
-    /* Make sure we can roundtrip to json without any changes. */           \
-    std::string as_json;                                                    \
-    std::string unused;                                                     \
-    EXPECT_TRUE(commands::FormatStringToString(                             \
-        out_again, commands::TreeDumpMode::kJSON, &unused, &as_json));      \
-    std::string rewritten;                                                  \
-    EXPECT_TRUE(commands::FormatJsonToString(as_json, &rewritten));         \
-    ASSERT_EQ(out, rewritten);                                              \
+#define FORMAT_TEST(n) FORMAT_TEST_WITH_WIDTH(n, commands::kDefaultFormatWidth)
+
+#define FORMAT_TEST_WITH_WIDTH(n, format_width)                                \
+  TEST_F(FormatTest, n) {                                                      \
+    ::Setup setup;                                                             \
+    std::string input;                                                         \
+    std::string out;                                                           \
+    std::string expected;                                                      \
+    base::FilePath src_dir =                                                   \
+        GetExePath().DirName().Append(FILE_PATH_LITERAL(".."));                \
+    base::SetCurrentDirectory(src_dir);                                        \
+    ASSERT_TRUE(base::ReadFileToString(                                        \
+        base::FilePath(FILE_PATH_LITERAL("src/gn/format_test_data/")           \
+                           FILE_PATH_LITERAL(#n) FILE_PATH_LITERAL(".gn")),    \
+        &input));                                                              \
+    ASSERT_TRUE(base::ReadFileToString(                                        \
+        base::FilePath(FILE_PATH_LITERAL("src/gn/format_test_data/")           \
+                           FILE_PATH_LITERAL(#n)                               \
+                               FILE_PATH_LITERAL(".golden")),                  \
+        &expected));                                                           \
+    EXPECT_TRUE(commands::FormatStringToString(                                \
+        input, commands::TreeDumpMode::kInactive, format_width, &out,          \
+        nullptr));                                                             \
+    EXPECT_EQ(expected, out);                                                  \
+    /* Make sure formatting the output doesn't cause further changes. */       \
+    std::string out_again;                                                     \
+    EXPECT_TRUE(                                                               \
+        commands::FormatStringToString(out, commands::TreeDumpMode::kInactive, \
+                                       format_width, &out_again, nullptr));    \
+    ASSERT_EQ(out, out_again);                                                 \
+    /* Make sure we can roundtrip to json without any changes. */              \
+    std::string as_json;                                                       \
+    std::string unused;                                                        \
+    EXPECT_TRUE(commands::FormatStringToString(                                \
+        out_again, commands::TreeDumpMode::kJSON, format_width, &unused,       \
+        &as_json));                                                            \
+    std::string rewritten;                                                     \
+    EXPECT_TRUE(                                                               \
+        commands::FormatJsonToString(as_json, format_width, &rewritten));      \
+    ASSERT_EQ(out, rewritten);                                                 \
   }
 
 // These are expanded out this way rather than a runtime loop so that
@@ -158,3 +164,4 @@
 FORMAT_TEST(103)
 FORMAT_TEST(104)
 FORMAT_TEST(105)
+FORMAT_TEST_WITH_WIDTH(106, 20)
diff --git a/src/gn/format_test_data/106.gn b/src/gn/format_test_data/106.gn
new file mode 100644
index 0000000..c49d312
--- /dev/null
+++ b/src/gn/format_test_data/106.gn
@@ -0,0 +1 @@
+# This is a line that exceeds the formatting width of 20
diff --git a/src/gn/format_test_data/106.golden b/src/gn/format_test_data/106.golden
new file mode 100644
index 0000000..3497b38
--- /dev/null
+++ b/src/gn/format_test_data/106.golden
@@ -0,0 +1,4 @@
+# This is a line
+# that exceeds the
+# formatting width
+# of 20
diff --git a/src/gn/setup.cc b/src/gn/setup.cc
index 555e34c..132d711 100644
--- a/src/gn/setup.cc
+++ b/src/gn/setup.cc
@@ -15,6 +15,7 @@
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/memory/ref_counted.h"
+#include "base/strings/string_number_conversions.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
@@ -690,7 +691,8 @@
 
   std::string contents = args_input_file_->contents();
   commands::FormatStringToString(contents, commands::TreeDumpMode::kInactive,
-                                 &contents, nullptr);
+                                 commands::kDefaultFormatWidth, &contents,
+                                 nullptr);
 #if defined(OS_WIN)
   // Use Windows lineendings for this file since it will often open in
   // Notepad which can't handle Unix ones.
diff --git a/src/gn/setup.h b/src/gn/setup.h
index 59ec134..4004891 100644
--- a/src/gn/setup.h
+++ b/src/gn/setup.h
@@ -63,6 +63,10 @@
                       const base::CommandLine& cmdline,
                       Err* err);
 
+  // Setup just enough data for the 'format' command, which doesn't require
+  // a build directory.
+  bool DoSetupForFormat();
+
   // Runs the load, returning true on success. On failure, prints the error
   // and returns false. This includes both RunPreMessageLoop() and
   // RunPostMessageLoop().
diff --git a/src/gn/switches.cc b/src/gn/switches.cc
index 5442776..61b3425 100644
--- a/src/gn/switches.cc
+++ b/src/gn/switches.cc
@@ -112,6 +112,17 @@
   flag to force GN to fail in that case.
 )";
 
+const char kFormatWidth[] = "format-width";
+const char kFormatWidth_HelpShort[] =
+    "--format-width: Set the formatting width (default is 80)";
+
+const char kFormatWidth_Help[] =
+    R"("--format-width: Set the formatting width,
+
+  Override the format width (default is 80) used by the 'format'
+  command. This takes a strictly positive integer decimal value.
+)";
+
 const char kMarkdown[] = "markdown";
 const char kMarkdown_HelpShort[] =
     "--markdown: Write help output in the Markdown format.";
@@ -359,6 +370,7 @@
     INSERT_VARIABLE(EnumerateFilesWithGit)
     INSERT_VARIABLE(ErrorLimit)
     INSERT_VARIABLE(FailOnUnusedArgs)
+    INSERT_VARIABLE(FormatWidth)
     INSERT_VARIABLE(Markdown)
     INSERT_VARIABLE(NinjaExecutable)
     INSERT_VARIABLE(NoColor)
diff --git a/src/gn/switches.h b/src/gn/switches.h
index 2c7c42b..70f0f19 100644
--- a/src/gn/switches.h
+++ b/src/gn/switches.h
@@ -50,6 +50,10 @@
 extern const char kFailOnUnusedArgs_HelpShort[];
 extern const char kFailOnUnusedArgs_Help[];
 
+extern const char kFormatWidth[];
+extern const char kFormatWidth_HelpShort[];
+extern const char kFormatWidth_Help[];
+
 extern const char kMarkdown[];
 extern const char kMarkdown_HelpShort[];
 extern const char kMarkdown_Help[];