Index: llvm/lib/Support/Triple.cpp
===================================================================
--- llvm/lib/Support/Triple.cpp
+++ llvm/lib/Support/Triple.cpp
@@ -1149,6 +1149,10 @@
     if (SubArch == MipsSubArch_r6)
       return "mipsisa64r6el";
     break;
+  case Triple::aarch64:
+    if (SubArch == AArch64SubArch_arm64ec)
+      return "arm64ec";
+    break;
   default:
     break;
   }
Index: llvm/unittests/ADT/TripleTest.cpp
===================================================================
--- llvm/unittests/ADT/TripleTest.cpp
+++ llvm/unittests/ADT/TripleTest.cpp
@@ -1990,6 +1990,16 @@
     EXPECT_EQ(Triple::aarch64, T.getArch());
     EXPECT_EQ(Triple::AArch64SubArch_arm64e, T.getSubArch());
   }
+  {
+    Triple T = Triple("arm64ec");
+    EXPECT_EQ(Triple::aarch64, T.getArch());
+    EXPECT_EQ(Triple::AArch64SubArch_arm64ec, T.getSubArch());
+  }
+  {
+    Triple T;
+    T.setArch(Triple::aarch64, Triple::AArch64SubArch_arm64ec);
+    EXPECT_EQ("arm64ec", T.getArchName());
+  }
 }
 
 TEST(TripleTest, isArmT32) {