diff --git a/llvm/include/llvm/ADT/Triple.h b/llvm/include/llvm/ADT/Triple.h
--- a/llvm/include/llvm/ADT/Triple.h
+++ b/llvm/include/llvm/ADT/Triple.h
@@ -19,6 +19,8 @@
 
 namespace llvm {
 
+class VersionTuple;
+
 /// Triple - Helper class for working with autoconf configuration names. For
 /// historical reasons, we also call these 'triples' (they used to contain
 /// exactly three fields).
@@ -438,17 +440,7 @@
   /// compatibility, which handles supporting skewed version numbering schemes
   /// used by the "darwin" triples.
   bool isMacOSXVersionLT(unsigned Major, unsigned Minor = 0,
-                         unsigned Micro = 0) const {
-    assert(isMacOSX() && "Not an OS X triple!");
-
-    // If this is OS X, expect a sane version number.
-    if (getOS() == Triple::MacOSX)
-      return isOSVersionLT(Major, Minor, Micro);
-
-    // Otherwise, compare to the "Darwin" number.
-    assert(Major == 10 && "Unexpected major version");
-    return isOSVersionLT(Minor + 4, Micro, 0);
-  }
+                         unsigned Micro = 0) const;
 
   /// isMacOSX - Is this a Mac OS X triple. For legacy reasons, we support both
   /// "darwin" and "osx" as OS X triples.
@@ -902,6 +894,10 @@
   static ArchType getArchTypeForLLVMName(StringRef Str);
 
   /// @}
+
+  /// Returns a canonicalized OS version number for the specified OS.
+  static VersionTuple getCanonicalVersionForOS(OSType OSKind,
+                                               const VersionTuple &Version);
 };
 
 } // End llvm namespace
diff --git a/llvm/lib/Support/Triple.cpp b/llvm/lib/Support/Triple.cpp
--- a/llvm/lib/Support/Triple.cpp
+++ b/llvm/lib/Support/Triple.cpp
@@ -15,6 +15,7 @@
 #include "llvm/Support/Host.h"
 #include "llvm/Support/SwapByteOrder.h"
 #include "llvm/Support/TargetParser.h"
+#include "llvm/Support/VersionTuple.h"
 #include <cassert>
 #include <cstring>
 using namespace llvm;
@@ -1086,17 +1087,23 @@
     // Darwin version numbers are skewed from OS X versions.
     if (Major < 4)
       return false;
-    Micro = 0;
-    Minor = Major - 4;
-    Major = 10;
+    if (Major <= 19) {
+      Micro = 0;
+      Minor = Major - 4;
+      Major = 10;
+    } else {
+      Micro = 0;
+      Minor = 0;
+      // darwin20+ corresponds to macOS 11+.
+      Major = 11 + Major - 20;
+    }
     break;
   case MacOSX:
     // Default to 10.4.
     if (Major == 0) {
       Major = 10;
       Minor = 4;
-    }
-    if (Major != 10)
+    } else if (Major < 10)
       return false;
     break;
   case IOS:
@@ -1600,6 +1607,23 @@
   return Other.str();
 }
 
+bool Triple::isMacOSXVersionLT(unsigned Major, unsigned Minor,
+                               unsigned Micro) const {
+  assert(isMacOSX() && "Not an OS X triple!");
+
+  // If this is OS X, expect a sane version number.
+  if (getOS() == Triple::MacOSX)
+    return isOSVersionLT(Major, Minor, Micro);
+
+  // Otherwise, compare to the "Darwin" number.
+  if (Major == 10) {
+    return isOSVersionLT(Minor + 4, Micro, 0);
+  } else {
+    assert(Major >= 11 && "Unexpected major version");
+    return isOSVersionLT(Major - 11 + 20, Minor, Micro);
+  }
+}
+
 StringRef Triple::getARMCPUForArch(StringRef MArch) const {
   if (MArch.empty())
     MArch = getArchName();
@@ -1662,3 +1686,16 @@
 
   llvm_unreachable("invalid arch name");
 }
+
+VersionTuple Triple::getCanonicalVersionForOS(OSType OSKind,
+                                              const VersionTuple &Version) {
+  switch (OSKind) {
+  case MacOSX:
+    // macOS 10.16 is canonicalized to macOS 11.
+    if (Version == VersionTuple(10, 16))
+      return VersionTuple(11, 0);
+    LLVM_FALLTHROUGH;
+  default:
+    return Version;
+  }
+}
diff --git a/llvm/unittests/ADT/TripleTest.cpp b/llvm/unittests/ADT/TripleTest.cpp
--- a/llvm/unittests/ADT/TripleTest.cpp
+++ b/llvm/unittests/ADT/TripleTest.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/ADT/Triple.h"
+#include "llvm/Support/VersionTuple.h"
 #include "gtest/gtest.h"
 
 using namespace llvm;
@@ -1222,6 +1223,44 @@
   EXPECT_EQ((unsigned)0, Minor);
   EXPECT_EQ((unsigned)0, Micro);
 
+  T = Triple("x86_64-apple-macos11.0");
+  EXPECT_TRUE(T.isMacOSX());
+  EXPECT_FALSE(T.isiOS());
+  EXPECT_FALSE(T.isArch16Bit());
+  EXPECT_FALSE(T.isArch32Bit());
+  EXPECT_TRUE(T.isArch64Bit());
+  T.getMacOSXVersion(Major, Minor, Micro);
+  EXPECT_EQ((unsigned)11, Major);
+  EXPECT_EQ((unsigned)0, Minor);
+  EXPECT_EQ((unsigned)0, Micro);
+
+  T = Triple("arm64-apple-macosx11.5.8");
+  EXPECT_TRUE(T.isMacOSX());
+  EXPECT_FALSE(T.isiOS());
+  EXPECT_FALSE(T.isArch16Bit());
+  EXPECT_FALSE(T.isArch32Bit());
+  EXPECT_TRUE(T.isArch64Bit());
+  T.getMacOSXVersion(Major, Minor, Micro);
+  EXPECT_EQ((unsigned)11, Major);
+  EXPECT_EQ((unsigned)5, Minor);
+  EXPECT_EQ((unsigned)8, Micro);
+
+  // 10.16 forms a valid triple, even though it's not
+  // a version of a macOS.
+  T = Triple("x86_64-apple-macos10.16");
+  EXPECT_TRUE(T.isMacOSX());
+  T.getMacOSXVersion(Major, Minor, Micro);
+  EXPECT_EQ((unsigned)10, Major);
+  EXPECT_EQ((unsigned)16, Minor);
+  EXPECT_EQ((unsigned)0, Micro);
+
+  T = Triple("x86_64-apple-darwin20");
+  EXPECT_TRUE(T.isMacOSX());
+  T.getMacOSXVersion(Major, Minor, Micro);
+  EXPECT_EQ((unsigned)11, Major);
+  EXPECT_EQ((unsigned)0, Minor);
+  EXPECT_EQ((unsigned)0, Micro);
+
   T = Triple("armv7-apple-ios");
   EXPECT_FALSE(T.isMacOSX());
   EXPECT_TRUE(T.isiOS());
@@ -1273,6 +1312,27 @@
   EXPECT_FALSE(T.isSimulatorEnvironment());
 }
 
+TEST(TripleTest, isMacOSVersionLT) {
+  Triple T = Triple("x86_64-apple-macos11");
+  EXPECT_TRUE(T.isMacOSXVersionLT(11, 1, 0));
+  EXPECT_FALSE(T.isMacOSXVersionLT(10, 15, 0));
+
+  T = Triple("x86_64-apple-darwin20");
+  EXPECT_TRUE(T.isMacOSXVersionLT(11, 1, 0));
+  EXPECT_FALSE(T.isMacOSXVersionLT(11, 0, 0));
+  EXPECT_FALSE(T.isMacOSXVersionLT(10, 15, 0));
+}
+
+TEST(TripleTest, CanonicalizeOSVersion) {
+  EXPECT_EQ(VersionTuple(10, 15, 4),
+            Triple::getCanonicalVersionForOS(Triple::MacOSX,
+                                             VersionTuple(10, 15, 4)));
+  EXPECT_EQ(VersionTuple(11, 0), Triple::getCanonicalVersionForOS(
+                                     Triple::MacOSX, VersionTuple(10, 16)));
+  EXPECT_EQ(VersionTuple(20),
+            Triple::getCanonicalVersionForOS(Triple::Darwin, VersionTuple(20)));
+}
+
 TEST(TripleTest, FileFormat) {
   EXPECT_EQ(Triple::ELF, Triple("i686-unknown-linux-gnu").getObjectFormat());
   EXPECT_EQ(Triple::ELF, Triple("i686-unknown-freebsd").getObjectFormat());