diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -748,6 +748,7 @@
                          [, comdat [($name)]] [, align <Alignment>]
                          [, no_sanitize] [, no_sanitize_address]
                          [, no_sanitize_hwaddress] [, sanitize_address_dyninit]
+                         [, sanitize_memtag] [, no_sanitize_memtag]
                          (, !name !N)*
 
 For example, the following defines a global in a numbered address space
@@ -2336,6 +2337,17 @@
     This attribute indicates that the global variable should not have
     HWAddressSanitizer instrumentation applied to it, because it was annotated
     with `__attribute__((no_sanitize("hwaddress")))`.
+``no_sanitize_memtag``
+    This attribute indicates that the global variable should not have AArch64
+    memory tags (MTE) instrumentation applied to it, because it was annotated
+    with `__attribute__((no_sanitize("memtag")))`.
+``sanitize_memtag``
+    This attribute indicates that the global variable should have AArch64 memory
+    tags (MTE) instrumentation applied to it. This attribute causes the
+    suppression of certain optimisations, like GlobalMerge, as well as ensuring
+    extra directives are emitted in the assembly and extra bits of metadata are
+    placed in the object file so that the linker can ensure the accesses are
+    protected by MTE.
 ``sanitize_address_dyninit``
     This attribute indicates that the global variable, when instrumented with
     AddressSanitizer, should be checked for ODR violations. This attribute is
diff --git a/llvm/include/llvm/IR/GlobalValue.h b/llvm/include/llvm/IR/GlobalValue.h
--- a/llvm/include/llvm/IR/GlobalValue.h
+++ b/llvm/include/llvm/IR/GlobalValue.h
@@ -311,10 +311,23 @@
   struct SanitizerMetadata {
     SanitizerMetadata()
         : NoAddress(false), NoHWAddress(false), NoMemtag(false),
-          IsDynInit(false) {}
+          Memtag(false), IsDynInit(false) {}
     unsigned NoAddress : 1;
     unsigned NoHWAddress : 1;
+
+    // Memtag has both an include- and exclude-bit. The exclude-bit (as
+    // described above) is added by clang and used to control selection in the
+    // memtag globals tagging pass. The include-bit is added by the memtag
+    // globals tagging pass, and is used by the Asm writer / ELF writers to
+    // create special assembly directives, sections, relocations, and supression
+    // of certain optimisations. ASan/HWASan do not need an include-bit, as they
+    // simply rewrite the global variable and accesses, and don't need to
+    // interact with other parts of LLVM.
+    //
+    // Use `GlobalValue::isTagged()` to check whether tagging should be enabled
+    // for a global variable.
     unsigned NoMemtag : 1;
+    unsigned Memtag : 1;
 
     // ASan-specific metadata. Is this global variable dynamically initialized
     // (from a C++ language perspective), and should therefore be checked for
@@ -331,6 +344,12 @@
   void setSanitizerMetadata(SanitizerMetadata Meta);
   void removeSanitizerMetadata();
 
+  bool isTagged() const {
+    if (!hasSanitizerMetadata()) return false;
+    const SanitizerMetadata& Meta = getSanitizerMetadata();
+    return Meta.Memtag && !Meta.NoMemtag;
+  }
+
   static LinkageTypes getLinkOnceLinkage(bool ODR) {
     return ODR ? LinkOnceODRLinkage : LinkOnceAnyLinkage;
   }
diff --git a/llvm/lib/AsmParser/LLParser.cpp b/llvm/lib/AsmParser/LLParser.cpp
--- a/llvm/lib/AsmParser/LLParser.cpp
+++ b/llvm/lib/AsmParser/LLParser.cpp
@@ -1108,6 +1108,7 @@
   case lltok::kw_no_sanitize_address:
   case lltok::kw_no_sanitize_hwaddress:
   case lltok::kw_no_sanitize_memtag:
+  case lltok::kw_sanitize_memtag:
   case lltok::kw_sanitize_address_dyninit:
     return true;
   default:
@@ -1131,6 +1132,9 @@
   case lltok::kw_no_sanitize_memtag:
     Meta.NoMemtag = true;
     break;
+  case lltok::kw_sanitize_memtag:
+    Meta.Memtag = true;
+    break;
   case lltok::kw_sanitize_address_dyninit:
     Meta.IsDynInit = true;
     break;
diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -3674,6 +3674,8 @@
     Meta.NoMemtag = true;
   if (V & (1 << 3))
     Meta.IsDynInit = true;
+  if (V & (1 << 4))
+    Meta.Memtag = true;
   return Meta;
 }
 
diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -1230,7 +1230,7 @@
 static unsigned
 serializeSanitizerMetadata(const GlobalValue::SanitizerMetadata &Meta) {
   return Meta.NoAddress | (Meta.NoHWAddress << 1) |
-         (Meta.NoMemtag << 2) | (Meta.IsDynInit << 3);
+         (Meta.NoMemtag << 2) | (Meta.IsDynInit << 3) | (Meta.Memtag << 4);
 }
 
 /// Emit top-level description of module, including target triple, inline asm,
diff --git a/llvm/lib/IR/AsmWriter.cpp b/llvm/lib/IR/AsmWriter.cpp
--- a/llvm/lib/IR/AsmWriter.cpp
+++ b/llvm/lib/IR/AsmWriter.cpp
@@ -3544,6 +3544,8 @@
       Out << ", no_sanitize_hwaddress";
     if (MD.NoMemtag)
       Out << ", no_sanitize_memtag";
+    if (MD.Memtag)
+      Out << ", sanitize_memtag";
     if (MD.IsDynInit)
       Out << ", sanitize_address_dyninit";
   }
diff --git a/llvm/test/Assembler/globalvariable-attributes.ll b/llvm/test/Assembler/globalvariable-attributes.ll
--- a/llvm/test/Assembler/globalvariable-attributes.ll
+++ b/llvm/test/Assembler/globalvariable-attributes.ll
@@ -9,6 +9,9 @@
 @g7 = global i32 2, no_sanitize_memtag, align 4
 @g8 = global i32 2, sanitize_address_dyninit, align 4
 @g9 = global i32 2, no_sanitize_address, no_sanitize_hwaddress, no_sanitize_memtag, align 4
+@g10 = global i32 2, sanitize_memtag, align 4
+@g11 = global i32 2, no_sanitize_memtag, sanitize_memtag, align 4
+@g12 = global i32 2, no_sanitize_address, no_sanitize_hwaddress, sanitize_memtag, align 4
 
 attributes #0 = { "string" = "value" nobuiltin norecurse }
 
@@ -21,6 +24,9 @@
 ; CHECK: @g7 = global i32 2, no_sanitize_memtag, align 4
 ; CHECK: @g8 = global i32 2, sanitize_address_dyninit, align 4
 ; CHECK: @g9 = global i32 2, no_sanitize_address, no_sanitize_hwaddress, no_sanitize_memtag, align 4
+; CHECK: @g10 = global i32 2, sanitize_memtag, align 4
+; CHECK: @g11 = global i32 2, no_sanitize_memtag, sanitize_memtag, align 4
+; CHECK: @g12 = global i32 2, no_sanitize_address, no_sanitize_hwaddress, sanitize_memtag, align 4
 
 ; CHECK: attributes #0 = { "key"="value" "key2"="value2" }
 ; CHECK: attributes #1 = { "key3"="value3" }
diff --git a/llvm/test/Bitcode/compatibility.ll b/llvm/test/Bitcode/compatibility.ll
--- a/llvm/test/Bitcode/compatibility.ll
+++ b/llvm/test/Bitcode/compatibility.ll
@@ -207,11 +207,15 @@
 @g.no_sanitize_address = global i32 0, no_sanitize_address
 @g.no_sanitize_hwaddress = global i32 0, no_sanitize_hwaddress
 @g.no_sanitize_memtag = global i32 0, no_sanitize_memtag
+@g.sanitize_memtag = global i32 0, sanitize_memtag
+@g.sanitize_and_nosanitize_memtag = global i32 0, no_sanitize_memtag, sanitize_memtag
 @g.no_sanitize_multiple = global i32 0, no_sanitize_address, no_sanitize_hwaddress, no_sanitize_memtag
 @g.sanitize_address_dyninit = global i32 0, sanitize_address_dyninit
 ; CHECK: @g.no_sanitize_address = global i32 0, no_sanitize_address
 ; CHECK: @g.no_sanitize_hwaddress = global i32 0, no_sanitize_hwaddress
 ; CHECK: @g.no_sanitize_memtag = global i32 0, no_sanitize_memtag
+; CHECK: @g.sanitize_memtag = global i32 0, sanitize_memtag
+; CHECK: @g.sanitize_and_nosanitize_memtag = global i32 0, no_sanitize_memtag, sanitize_memtag
 ; CHECK: @g.no_sanitize_multiple = global i32 0, no_sanitize_address, no_sanitize_hwaddress, no_sanitize_memtag
 ; CHECK: @g.sanitize_address_dyninit = global i32 0, sanitize_address_dyninit