Index: llvm/docs/AMDGPUUsage.rst
===================================================================
--- llvm/docs/AMDGPUUsage.rst
+++ llvm/docs/AMDGPUUsage.rst
@@ -1387,6 +1387,7 @@
      ``AMD:AMDGPU:9:0:5`` ``gfx904:xnack+``
      ``AMD:AMDGPU:9:0:6`` ``gfx906:sramecc-:xnack-``
      ``AMD:AMDGPU:9:0:7`` ``gfx906:sramecc-:xnack+``
+     ``AMD:AMDGPU:9:0:C`` ``gfx90c:xnack-``
      ==================== ==========================
 
 .. _amdgpu-note-records-v3-v4:
Index: llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.cpp
+++ llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.cpp
@@ -438,7 +438,13 @@
       } else if (Processor == "gfx906") {
         if (isXnackOnOrAny())
           Processor = "gfx907";
-      } else {
+      } else if (Processor == "gfx90c") {
+        if (isXnackOnOrAny())
+          report_fatal_error(
+              "AMD GPU code object V2 does not support processor " + Processor +
+              " with XNACK being ON or ANY");
+      }
+      else {
         report_fatal_error(
             "AMD GPU code object V2 does not support processor " + Processor);
       }
Index: llvm/test/CodeGen/AMDGPU/tid-code-object-v2-backwards-compatibility.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/AMDGPU/tid-code-object-v2-backwards-compatibility.ll
@@ -0,0 +1,5 @@
+; RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx90c -mattr=-xnack --amdhsa-code-object-version=2 < %s 2>&1 | FileCheck --check-prefix=GFX90C-VALID %s
+; RUN: not --crash llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx90c --amdhsa-code-object-version=2 < %s 2>&1 | FileCheck --check-prefix=GFX90C-ERROR %s
+
+; GFX90C-VALID: .amd_amdgpu_isa "amdgcn-amd-amdhsa--gfx90c"
+; GFX90C-ERROR: LLVM ERROR: AMD GPU code object V2 does not support processor gfx90c with XNACK being ON or ANY