Index: clang/include/clang/Basic/DiagnosticOptions.def
===================================================================
--- clang/include/clang/Basic/DiagnosticOptions.def
+++ clang/include/clang/Basic/DiagnosticOptions.def
@@ -47,6 +47,7 @@
 DIAGOPT(NoRewriteMacros, 1, 0)  /// -Wno-rewrite-macros
 DIAGOPT(Pedantic, 1, 0)         /// -pedantic
 DIAGOPT(PedanticErrors, 1, 0)   /// -pedantic-errors
+DIAGOPT(ShowLine, 1, 1)         /// Show line number on diagnostics.
 DIAGOPT(ShowColumn, 1, 1)       /// Show column number on diagnostics.
 DIAGOPT(ShowLocation, 1, 1)     /// Show source location information.
 DIAGOPT(ShowLevel, 1, 1)        /// Show diagnostic level.
Index: clang/lib/Frontend/TextDiagnostic.cpp
===================================================================
--- clang/lib/Frontend/TextDiagnostic.cpp
+++ clang/lib/Frontend/TextDiagnostic.cpp
@@ -827,7 +827,10 @@
 
   emitFilename(PLoc.getFilename(), Loc.getManager());
   switch (DiagOpts->getFormat()) {
-  case DiagnosticOptions::Clang: OS << ':'  << LineNo; break;
+  case DiagnosticOptions::Clang:
+    if (DiagOpts->ShowLine)
+      OS << ':' << LineNo;
+    break;
   case DiagnosticOptions::MSVC:  OS << '('  << LineNo; break;
   case DiagnosticOptions::Vi:    OS << " +" << LineNo; break;
   }
Index: clang/unittests/Frontend/CMakeLists.txt
===================================================================
--- clang/unittests/Frontend/CMakeLists.txt
+++ clang/unittests/Frontend/CMakeLists.txt
@@ -12,6 +12,7 @@
   ParsedSourceLocationTest.cpp
   PCHPreambleTest.cpp
   OutputStreamTest.cpp
+  TextDiagnosticTest.cpp
   )
 clang_target_link_libraries(FrontendTests
   PRIVATE
Index: clang/unittests/Frontend/TextDiagnosticTest.cpp
===================================================================
--- /dev/null
+++ clang/unittests/Frontend/TextDiagnosticTest.cpp
@@ -0,0 +1,100 @@
+//===- unittests/Frontend/TextDiagnosticTest.cpp - ------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Frontend/TextDiagnostic.h"
+#include "clang/Basic/FileManager.h"
+#include "clang/Basic/LangOptions.h"
+#include "clang/Basic/SourceManager.h"
+#include "llvm/Support/SmallVectorMemoryBuffer.h"
+#include "gtest/gtest.h"
+
+using namespace llvm;
+using namespace clang;
+
+namespace {
+
+/// Prints a diagnostic with the given DiagnosticOptions and the given
+/// SourceLocation and returns the printed diagnostic text.
+static std::string PrintDiag(const DiagnosticOptions &Opts, FullSourceLoc Loc) {
+  std::string Out;
+  llvm::raw_string_ostream OS(Out);
+  clang::LangOptions LangOpts;
+  // Owned by TextDiagnostic.
+  DiagnosticOptions *DiagOpts = new DiagnosticOptions(Opts);
+  TextDiagnostic Diag(OS, LangOpts, DiagOpts);
+  // Emit a dummy diagnostic that is just 'message'.
+  Diag.emitDiagnostic(Loc, DiagnosticsEngine::Level::Warning, "message",
+                      /*Ranges=*/ {}, /*FixItHints=*/ {});
+  OS.flush();
+  return Out;
+}
+
+TEST(TextDiagnostic, ShowLine) {
+  // Create dummy FileManager and SourceManager.
+  FileSystemOptions FSOpts;
+  FileManager FileMgr(FSOpts);
+  IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs);
+  DiagnosticsEngine DiagEngine(DiagID, new DiagnosticOptions,
+                               new IgnoringDiagConsumer());
+  SourceManager SrcMgr(DiagEngine, FileMgr);
+
+  // Create a dummy file with some contents to produce a test SourceLocation.
+  const llvm::StringRef file_path = "main.cpp";
+  const llvm::StringRef main_file_contents = "some\nsource\ncode\n";
+  const clang::FileEntry &fe = *FileMgr.getVirtualFile(
+      file_path,
+      /*file_size*/ static_cast<off_t>(main_file_contents.size()),
+      /*mod_time*/ 0);
+
+  llvm::SmallVector<char, 64> buffer;
+  buffer.append(main_file_contents.begin(), main_file_contents.end());
+  auto file_contents = std::make_unique<llvm::SmallVectorMemoryBuffer>(
+      std::move(buffer), file_path);
+  SrcMgr.overrideFileContents(&fe, std::move(file_contents));
+
+  // Create the actual file id and use it as the main file.
+  clang::FileID fid =
+      SrcMgr.createFileID(&fe, SourceLocation(), clang::SrcMgr::C_User);
+  SrcMgr.setMainFileID(fid);
+
+  // Create the source location for the test diagnostic.
+  FullSourceLoc Loc(SrcMgr.translateLineCol(fid, /*line*/ 1, /*col*/ 2),
+                    SrcMgr);
+
+  DiagnosticOptions DiagOpts;
+  DiagOpts.ShowLine = true;
+  DiagOpts.ShowColumn = true;
+  // Hide printing the source line/caret to make the diagnostic shorter and it's
+  // not relevant for this test.
+  DiagOpts.ShowCarets = false;
+  EXPECT_EQ("main.cpp:1:2: warning: message\n", PrintDiag(DiagOpts, Loc));
+
+  // Check that ShowLine doesn't influence the Vi/MSVC diagnostic formats as its
+  // a Clang-specific diagnostic option.
+  DiagOpts.setFormat(TextDiagnosticFormat::Vi);
+  DiagOpts.ShowLine = false;
+  EXPECT_EQ("main.cpp +1:2: warning: message\n", PrintDiag(DiagOpts, Loc));
+
+  DiagOpts.setFormat(TextDiagnosticFormat::MSVC);
+  DiagOpts.ShowLine = false;
+  EXPECT_EQ("main.cpp(1,2): warning: message\n", PrintDiag(DiagOpts, Loc));
+
+  // Reset back to the Clang format.
+  DiagOpts.setFormat(TextDiagnosticFormat::Clang);
+
+  // Hide line number but show column.
+  DiagOpts.ShowLine = false;
+  EXPECT_EQ("main.cpp:2: warning: message\n", PrintDiag(DiagOpts, Loc));
+
+  // Show line number but hide column.
+  DiagOpts.ShowLine = true;
+  DiagOpts.ShowColumn = false;
+  EXPECT_EQ("main.cpp:1: warning: message\n", PrintDiag(DiagOpts, Loc));
+}
+
+} // anonymous namespace