diff --git a/clang/include/clang/Basic/DiagnosticDriverKinds.td b/clang/include/clang/Basic/DiagnosticDriverKinds.td
--- a/clang/include/clang/Basic/DiagnosticDriverKinds.td
+++ b/clang/include/clang/Basic/DiagnosticDriverKinds.td
@@ -29,6 +29,8 @@
   "invalid arch name '%0'">;
 def err_drv_invalid_riscv_arch_name : Error<
   "invalid arch name '%0', %1">;
+def err_drv_invalid_riscv_cpu_name_for_target : Error<
+  "cpu '%0' does not support rv%select{32|64}1">;
 def warn_drv_invalid_arch_name_with_suggestion : Warning<
   "ignoring invalid /arch: argument '%0'; for %select{64|32}1-bit expected one of %2">,
   InGroup<UnusedCommandLineArgument>;
diff --git a/clang/lib/Driver/ToolChains/Arch/RISCV.cpp b/clang/lib/Driver/ToolChains/Arch/RISCV.cpp
--- a/clang/lib/Driver/ToolChains/Arch/RISCV.cpp
+++ b/clang/lib/Driver/ToolChains/Arch/RISCV.cpp
@@ -49,14 +49,20 @@
 }
 
 // Get features except standard extension feature
-static void getRISCFeaturesFromMcpu(const Driver &D, const llvm::Triple &Triple,
+static void getRISCFeaturesFromMcpu(const Driver &D, const Arg *A,
+                                    const llvm::Triple &Triple,
                                     StringRef Mcpu,
                                     std::vector<StringRef> &Features) {
   bool Is64Bit = Triple.isRISCV64();
   llvm::RISCV::CPUKind CPUKind = llvm::RISCV::parseCPUKind(Mcpu);
-  if (!llvm::RISCV::checkCPUKind(CPUKind, Is64Bit))
-    D.Diag(clang::diag::err_drv_unsupported_option_argument)
-        << A->getSpelling() << CPU;
+  if (!llvm::RISCV::checkCPUKind(CPUKind, Is64Bit)) {
+    // Try inverting Is64Bit in case the CPU is valid, but for the wrong target.
+    if (llvm::RISCV::checkCPUKind(CPUKind, !Is64Bit))
+      D.Diag(clang::diag::err_drv_invalid_riscv_cpu_name_for_target) << Mcpu << Is64Bit;
+    else
+      D.Diag(clang::diag::err_drv_unsupported_option_argument)
+          << A->getSpelling() << Mcpu;
+  }
 }
 
 void riscv::getRISCVTargetFeatures(const Driver &D, const llvm::Triple &Triple,
@@ -74,7 +80,7 @@
     if (CPU == "native")
       CPU = llvm::sys::getHostCPUName();
 
-    getRISCFeaturesFromMcpu(D, Triple, CPU, Features);
+    getRISCFeaturesFromMcpu(D, A, Triple, CPU, Features);
   }
 
   // Handle features corresponding to "-ffixed-X" options
diff --git a/clang/test/Driver/riscv-cpus.c b/clang/test/Driver/riscv-cpus.c
--- a/clang/test/Driver/riscv-cpus.c
+++ b/clang/test/Driver/riscv-cpus.c
@@ -173,7 +173,7 @@
 // FAIL-MCPU-NAME: error: unsupported argument 'generic-rv321' to option '-mcpu='
 
 // RUN: %clang --target=riscv32 -### -c %s 2>&1 -mcpu=generic-rv32 -march=rv64i | FileCheck -check-prefix=MISMATCH-ARCH %s
-// MISMATCH-ARCH: error: unsupported argument 'generic-rv32' to option '-mcpu='
+// MISMATCH-ARCH: cpu 'generic-rv32' does not support rv64
 
 // RUN: %clang --target=riscv32 -### -c %s 2>&1 -mcpu=generic-rv64 | FileCheck -check-prefix=MISMATCH-MCPU %s
-// MISMATCH-MCPU: error: unsupported argument 'generic-rv64' to option '-mcpu='
+// MISMATCH-MCPU: error: cpu 'generic-rv64' does not support rv32