Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -422,6 +422,9 @@
 - Fixed incorrect ABI lowering of ``_Float16`` in the case of structs
   containing ``_Float16`` that are eligible for passing via GPR+FPR or
   FPR+FPR.
+- The rules for ordering of extensions in ``-march`` strings were relaxed. A
+  canonical ordering is no longer enforced on ``z*``, ``s*``, and ``x*``
+  prefixed extensions.
 
 CUDA/HIP Language Changes
 ^^^^^^^^^^^^^^^^^^^^^^^^^
Index: clang/test/Driver/riscv-arch.c
===================================================================
--- clang/test/Driver/riscv-arch.c
+++ clang/test/Driver/riscv-arch.c
@@ -333,8 +333,7 @@
 // RUN: %clang --target=riscv32-unknown-elf -march=rv32ixdef_sabc -### %s \
 // RUN: -fsyntax-only 2>&1 | FileCheck -check-prefix=RV32-X-ORDER %s
 // RV32-X-ORDER: error: invalid arch name 'rv32ixdef_sabc',
-// RV32-X-ORDER: standard supervisor-level extension not given
-// RV32-X-ORDER: in canonical order 'sabc'
+// RV32-X-ORDER  unsupported non-standard user-level extension 'xdef'
 
 // RUN: %clang --target=riscv32-unknown-elf -march=rv32ixabc_xabc -### %s \
 // RUN: -fsyntax-only 2>&1 | FileCheck -check-prefix=RV32-XDUP %s
Index: llvm/lib/Support/RISCVISAInfo.cpp
===================================================================
--- llvm/lib/Support/RISCVISAInfo.cpp
+++ llvm/lib/Support/RISCVISAInfo.cpp
@@ -767,9 +767,6 @@
   OtherExts.split(Split, '_');
 
   SmallVector<StringRef, 8> AllExts;
-  std::array<StringRef, 4> Prefix{"z", "s", "x"};
-  auto I = Prefix.begin();
-  auto E = Prefix.end();
   if (Split.size() > 1 || Split[0] != "") {
     for (StringRef Ext : Split) {
       if (Ext.empty())
@@ -789,18 +786,6 @@
                                  "invalid extension prefix '" + Ext + "'");
       }
 
-      // Check ISA extensions are specified in the canonical order.
-      while (I != E && *I != Type)
-        ++I;
-
-      if (I == E) {
-        if (IgnoreUnknown)
-          continue;
-        return createStringError(errc::invalid_argument,
-                                 "%s not given in canonical order '%s'",
-                                 Desc.str().c_str(), Ext.str().c_str());
-      }
-
       if (!IgnoreUnknown && Name.size() == Type.size()) {
         return createStringError(errc::invalid_argument,
                                  "%s name missing after '%s'",
Index: llvm/unittests/Support/RISCVISAInfoTest.cpp
===================================================================
--- llvm/unittests/Support/RISCVISAInfoTest.cpp
+++ llvm/unittests/Support/RISCVISAInfoTest.cpp
@@ -192,7 +192,7 @@
   EXPECT_EQ(InfoRV64G.getFLen(), 64U);
 }
 
-TEST(ParseArchString, RequiresCanonicalOrderForExtensions) {
+TEST(ParseArchString, RequiresCanonicalOrderForSingleLetterExtensions) {
   EXPECT_EQ(
       toString(RISCVISAInfo::parseArchString("rv64idf", true).takeError()),
       "standard user-level extension not given in canonical order 'f'");
@@ -203,12 +203,10 @@
       toString(
           RISCVISAInfo::parseArchString("rv32i_zfinx_a", true).takeError()),
       "invalid extension prefix 'a'");
-  EXPECT_EQ(
-      toString(RISCVISAInfo::parseArchString("rv64i_svnapot_zicsr", true)
-                   .takeError()),
-      "standard user-level extension not given in canonical order 'zicsr'");
+  // Canonical ordering not required for z*, s*, and x* extensions.
   EXPECT_THAT_EXPECTED(
-      RISCVISAInfo::parseArchString("rv64imafdc_zicsr_svnapot", true),
+      RISCVISAInfo::parseArchString(
+          "rv64imafdc_xsfvcp_zicsr_xtheadba_svnapot_zawrs", true),
       Succeeded());
 }