diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -7903,6 +7903,12 @@
 
   CmdArgs.push_back("-target-abi");
   CmdArgs.push_back(ABIName.data());
+
+  if (Args.hasFlag(options::OPT_mdefault_build_attributes,
+                   options::OPT_mno_default_build_attributes, true)) {
+      CmdArgs.push_back("-mllvm");
+      CmdArgs.push_back("-riscv-add-build-attributes");
+  }
 }
 
 void ClangAs::ConstructJob(Compilation &C, const JobAction &JA,
diff --git a/clang/test/Driver/riscv-default-build-attributes.s b/clang/test/Driver/riscv-default-build-attributes.s
new file mode 100644
--- /dev/null
+++ b/clang/test/Driver/riscv-default-build-attributes.s
@@ -0,0 +1,20 @@
+//// Enabled by default for assembly
+// RUN: %clang --target=riscv64 -### %s 2>&1 \
+// RUN:    | FileCheck %s -check-prefix CHECK-ENABLED
+
+/// Can be forced on or off for assembly.
+// RUN: %clang --target=riscv64 -### %s 2>&1 -mno-default-build-attributes \
+// RUN:    | FileCheck %s -check-prefix CHECK-DISABLED
+// RUN: %clang --target=riscv64 -### %s 2>&1 -mdefault-build-attributes \
+// RUN:    | FileCheck %s -check-prefix CHECK-ENABLED
+
+/// Option ignored for C/C++ (since we always emit hardware and ABI build
+/// attributes during codegen).
+// RUN: %clang --target=riscv64 -### -x c %s -mdefault-build-attributes 2>&1 \
+// RUN:    | FileCheck %s -check-prefix CHECK-DISABLED
+// RUN: %clang --target=riscv64 -### -x c++ %s -mdefault-build-attributes 2>&1 \
+// RUN:    | FileCheck %s -check-prefix CHECK-DISABLED
+
+// CHECK-DISABLED-NOT: "-riscv-add-build-attributes"
+// CHECK-ENABLED: "-riscv-add-build-attributes"
+// expected-warning {{argument unused during compilation: '-mno-default-build-attributes'}}