diff --git a/libc/src/math/round/round.h b/libc/src/math/round/round.h
--- a/libc/src/math/round/round.h
+++ b/libc/src/math/round/round.h
@@ -9,10 +9,10 @@
 #ifndef LLVM_LIBC_SRC_MATH_ROUND_H
 #define LLVM_LIBC_SRC_MATH_ROUND_H
 
-namespace llvm_libc {
+namespace __llvm_libc {
 
 double round(double x);
 
-} // namespace llvm_libc
+} // namespace __llvm_libc
 
 #endif // LLVM_LIBC_SRC_MATH_ROUND_H
diff --git a/libc/src/math/round/round.cpp b/libc/src/math/round/round.cpp
--- a/libc/src/math/round/round.cpp
+++ b/libc/src/math/round/round.cpp
@@ -10,7 +10,7 @@
 
 #include "src/__support/common.h"
 
-namespace llvm_libc {
+namespace __llvm_libc {
 
 double __round_redirector(double x);
 
@@ -18,4 +18,4 @@
   return __round_redirector(x);
 }
 
-} // namespace llvm_libc
+} // namespace __llvm_libc
diff --git a/libc/src/math/round/round_redirector.cpp b/libc/src/math/round/round_redirector.cpp
--- a/libc/src/math/round/round_redirector.cpp
+++ b/libc/src/math/round/round_redirector.cpp
@@ -8,10 +8,10 @@
 
 #include <math.h>
 
-namespace llvm_libc {
+namespace __llvm_libc {
 
 double __round_redirector(double x) {
   return ::round(x);
 }
 
-} // namespace llvm_libc
+} // namespace __llvm_libc