Index: libc/cmake/modules/LLVMLibCArchitectures.cmake
===================================================================
--- libc/cmake/modules/LLVMLibCArchitectures.cmake
+++ libc/cmake/modules/LLVMLibCArchitectures.cmake
@@ -17,6 +17,9 @@
 elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "^(powerpc|ppc)")
   set(LIBC_TARGET_ARCHITECTURE_IS_POWER TRUE)
   set(LIBC_TARGET_ARCHITECTURE "power")
+elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "^(riscv64|riscv)")
+  set(LIBC_TARGET_ARCHITECTURE_IS_POWER TRUE)
+  set(LIBC_TARGET_ARCHITECTURE "riscv")
 else()
   message(FATAL_ERROR "Unsupported processor ${CMAKE_SYSTEM_PROCESSOR}")
 endif()
Index: libc/src/__support/architectures.h
===================================================================
--- libc/src/__support/architectures.h
+++ libc/src/__support/architectures.h
@@ -33,6 +33,10 @@
 #define LLVM_LIBC_ARCH_AARCH64
 #endif
 
+#if defined(__riscv) || defined(__riscv__)
+#define LLVM_LIBC_ARCH_RISCV
+#endif
+
 #if (defined(LLVM_LIBC_ARCH_AARCH64) || defined(LLVM_LIBC_ARCH_ARM))
 #define LLVM_LIBC_ARCH_ANY_ARM
 #endif
Index: libc/src/string/memory_utils/utils.h
===================================================================
--- libc/src/string/memory_utils/utils.h
+++ libc/src/string/memory_utils/utils.h
@@ -15,7 +15,8 @@
 // cache line sizes depend on implementations, not architectures.  There
 // are even implementations with cache line sizes configurable at boot
 // time.
-#if defined(LLVM_LIBC_ARCH_AARCH64) || defined(LLVM_LIBC_ARCH_X86) || defined(LLVM_LIBC_ARCH_RISCV)
+#if defined(LLVM_LIBC_ARCH_AARCH64) || defined(LLVM_LIBC_ARCH_X86) ||          \
+    defined(LLVM_LIBC_ARCH_RISCV)
 #define LLVM_LIBC_CACHELINE_SIZE 64
 #else
 #error "Unsupported platform for memory functions."