Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -221,6 +221,8 @@
 - Clang now support ``__builtin_FUNCSIG()`` which returns the same information
   as the ``__FUNCSIG__`` macro (available only with ``-fms-extensions`` flag).
   This fixes (`#58951 <https://github.com/llvm/llvm-project/issues/58951>`_).
+- Clang now supports the `NO_COLOR <https://no-color.org/>`_ environment
+  variable as a way to disable color diagnostics.
 
 New Compiler Flags
 ------------------
Index: clang/docs/UsersManual.rst
===================================================================
--- clang/docs/UsersManual.rst
+++ clang/docs/UsersManual.rst
@@ -251,6 +251,11 @@
                 ^
                 //
 
+   If the ``NO_COLOR`` environment variable is defined (regardless of value),
+   color diagnostics are disabled. If ``NO_COLOR`` is defined and
+   ``-fcolor-diagnostics`` is passed on the command line, Clang will honor the
+   command line argument.
+
 .. option:: -fansi-escape-codes
 
    Controls whether ANSI escape codes are used instead of the Windows Console
Index: clang/lib/Frontend/CompilerInvocation.cpp
===================================================================
--- clang/lib/Frontend/CompilerInvocation.cpp
+++ clang/lib/Frontend/CompilerInvocation.cpp
@@ -2341,10 +2341,19 @@
   unsigned MissingArgIndex, MissingArgCount;
   InputArgList Args = getDriverOptTable().ParseArgs(
       Argv.slice(1), MissingArgIndex, MissingArgCount);
+
+  bool ShowColors = true;
+  if (std::optional<std::string> NoColor =
+          llvm::sys::Process::GetEnv("NO_COLOR")) {
+    // If the user set the NO_COLOR environment variable, we'll honor that
+    // unless the command line overrides it.
+    ShowColors = false;
+  }
+
   // We ignore MissingArgCount and the return value of ParseDiagnosticArgs.
   // Any errors that would be diagnosed here will also be diagnosed later,
   // when the DiagnosticsEngine actually exists.
-  (void)ParseDiagnosticArgs(*DiagOpts, Args);
+  (void)ParseDiagnosticArgs(*DiagOpts, Args, /*Diags=*/nullptr, ShowColors);
   return DiagOpts;
 }
 
Index: clang/test/Driver/no-color.c
===================================================================
--- /dev/null
+++ clang/test/Driver/no-color.c
@@ -0,0 +1,13 @@
+// RUN: env NO_COLOR= %clang -### %s 2>&1 | FileCheck --check-prefix=NO-COLOR %s
+// RUN: env NO_COLOR= %clang -fcolor-diagnostics -### %s 2>&1 | FileCheck --check-prefix=COLOR %s
+// RUN: env NO_COLOR= %clang -fdiagnostics-color=auto -### %s 2>&1 | FileCheck --check-prefix=NO-COLOR %s
+// RUN: env NO_COLOR= %clang -fdiagnostics-color=always -### %s 2>&1 | FileCheck --check-prefix=COLOR %s
+// RUN: env NO_COLOR= %clang -fdiagnostics-color=never -### %s 2>&1 | FileCheck --check-prefix=NO-COLOR %s
+
+// Note, the value of the environment variable does not matter, only that it is defined.
+// RUN: env NO_COLOR=0 %clang -### %s 2>&1 | FileCheck --check-prefix=NO-COLOR %s
+
+int main(void) {}
+
+// COLOR: -fcolor-diagnostics
+// NO-COLOR-NOT: -fcolor-diagnostics