diff --git a/libc/src/__support/FPUtil/aarch64/FEnvImpl.h b/libc/src/__support/FPUtil/aarch64/FEnvImpl.h
--- a/libc/src/__support/FPUtil/aarch64/FEnvImpl.h
+++ b/libc/src/__support/FPUtil/aarch64/FEnvImpl.h
@@ -67,13 +67,39 @@
            (status & INEXACT ? FE_INEXACT : 0);
   }
 
-  static uint32_t getControlWord() { return __arm_rsr("fpcr"); }
+  static uint32_t getControlWord() {
+#ifdef __clang__
+    // GCC does not currently support __arm_rsr.
+    return __arm_rsr("fpcr");
+#else
+    return __builtin_aarch64_get_fpcr();
+#endif
+  }
 
-  static void writeControlWord(uint32_t fpcr) { __arm_wsr("fpcr", fpcr); }
+  static void writeControlWord(uint32_t fpcr) {
+#ifdef __clang__
+    // GCC does not currently support __arm_wsr.
+    __arm_wsr("fpcr", fpcr);
+#else
+    __builtin_aarch64_set_fpcr(fpcr);
+#endif
+  }
 
-  static uint32_t getStatusWord() { return __arm_rsr("fpsr"); }
+  static uint32_t getStatusWord() {
+#ifdef __clang__
+    return __arm_rsr("fpsr");
+#else
+    return __builtin_aarch64_get_fpsr();
+#endif
+  }
 
-  static void writeStatusWord(uint32_t fpsr) { __arm_wsr("fpsr", fpsr); }
+  static void writeStatusWord(uint32_t fpsr) {
+#ifdef __clang__
+    __arm_wsr("fpsr", fpsr);
+#else
+    __builtin_aarch64_set_fpsr(fpsr);
+#endif
+  }
 };
 
 LIBC_INLINE int enable_except(int excepts) {
diff --git a/libc/src/__support/threads/linux/thread.cpp b/libc/src/__support/threads/linux/thread.cpp
--- a/libc/src/__support/threads/linux/thread.cpp
+++ b/libc/src/__support/threads/linux/thread.cpp
@@ -214,7 +214,12 @@
 #ifdef LIBC_TARGET_ARCH_IS_AARCH64
     // We set the frame pointer to be the same as the "sp" so that start args
     // can be sniffed out from start_thread.
+#ifdef __clang__
+    // GCC does not currently implement __arm_wsr64/__arm_rsr64.
     __arm_wsr64("x29", __arm_rsr64("sp"));
+#else
+    asm volatile("mov x29, sp");
+#endif
 #endif
     start_thread();
   } else if (clone_result < 0) {