diff --git a/libc/config/gpu/entrypoints.txt b/libc/config/gpu/entrypoints.txt
--- a/libc/config/gpu/entrypoints.txt
+++ b/libc/config/gpu/entrypoints.txt
@@ -84,6 +84,7 @@
 set(TARGET_LIBM_ENTRYPOINTS
     # math.h entrypoints
     libc.src.math.sin
+    libc.src.math.modf
 )
 
 set(TARGET_LLVMLIBC_ENTRYPOINTS
diff --git a/libc/src/math/gpu/CMakeLists.txt b/libc/src/math/gpu/CMakeLists.txt
--- a/libc/src/math/gpu/CMakeLists.txt
+++ b/libc/src/math/gpu/CMakeLists.txt
@@ -36,3 +36,18 @@
     ${bitcode_link_flags}
     -O2
 )
+
+add_entrypoint_object(
+  modf
+  SRCS
+    modf.cpp
+  HDRS
+    ../modf.h
+  COMPILE_OPTIONS
+    # FIXME: We need a way to pass the flag to only the NVTPX / AMDGPU build.
+    # This shouldn't cause issues because we only link in needed symbols, but it
+    # will link in identity metadata from both libraries.
+    -Wno-linker-warnings
+    ${bitcode_link_flags}
+    -O2
+)
\ No newline at end of file
diff --git a/libc/src/math/gpu/amdgpu/amdgpu.h b/libc/src/math/gpu/amdgpu/amdgpu.h
--- a/libc/src/math/gpu/amdgpu/amdgpu.h
+++ b/libc/src/math/gpu/amdgpu/amdgpu.h
@@ -17,6 +17,18 @@
 namespace __llvm_libc {
 namespace vendor {
 
+LIBC_INLINE double modf(double x, double *iptr) {
+  double tmp;
+#ifdef __OPENMP_AMDGCN__
+#pragma omp allocate(tmp) allocator(omp_thread_mem_alloc)
+#endif
+  double r =
+      __ocml_modf_f64(x, (__attribute__((address_space(5))) double *)&tmp);
+  *iptr = tmp;
+
+  return r;
+}
+
 LIBC_INLINE double sin(double x) { return __ocml_sin_f64(x); }
 
 } // namespace vendor
diff --git a/libc/src/math/gpu/amdgpu/declarations.h b/libc/src/math/gpu/amdgpu/declarations.h
--- a/libc/src/math/gpu/amdgpu/declarations.h
+++ b/libc/src/math/gpu/amdgpu/declarations.h
@@ -12,6 +12,7 @@
 namespace __llvm_libc {
 
 extern "C" {
+double __ocml_modf_f64(double,double*);
 double __ocml_sin_f64(double);
 }
 
diff --git a/libc/src/math/gpu/nvptx/declarations.h b/libc/src/math/gpu/modf.cpp
copy from libc/src/math/gpu/nvptx/declarations.h
copy to libc/src/math/gpu/modf.cpp
--- a/libc/src/math/gpu/nvptx/declarations.h
+++ b/libc/src/math/gpu/modf.cpp
@@ -1,4 +1,4 @@
-//===-- NVPTX specific declarations for math support ----------------------===//
+//===-- Implementation of the modf function for GPU ------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
@@ -6,15 +6,13 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef LLVM_LIBC_SRC_MATH_GPU_NVPTX_DECLARATIONS_H
-#define LLVM_LIBC_SRC_MATH_GPU_NVPTX_DECLARATIONS_H
+#include "src/math/modf.h"
+#include "src/__support/common.h"
 
-namespace __llvm_libc {
+#include "common.h"
 
-extern "C" {
-double __nv_sin(double);
-}
+namespace __llvm_libc {
 
-} // namespace __llvm_libc
+LLVM_LIBC_FUNCTION(double, modf, (double x,double *iptr)) { return internal::modf(x,iptr); }
 
-#endif // LLVM_LIBC_SRC_MATH_GPU_NVPTX_DECLARATIONS_H
+} // namespace __llvm_libc
\ No newline at end of file
diff --git a/libc/src/math/gpu/nvptx/declarations.h b/libc/src/math/gpu/nvptx/declarations.h
--- a/libc/src/math/gpu/nvptx/declarations.h
+++ b/libc/src/math/gpu/nvptx/declarations.h
@@ -12,6 +12,7 @@
 namespace __llvm_libc {
 
 extern "C" {
+double __nv_modf(double,double*);
 double __nv_sin(double);
 }
 
diff --git a/libc/src/math/gpu/nvptx/nvptx.h b/libc/src/math/gpu/nvptx/nvptx.h
--- a/libc/src/math/gpu/nvptx/nvptx.h
+++ b/libc/src/math/gpu/nvptx/nvptx.h
@@ -16,6 +16,7 @@
 namespace __llvm_libc {
 namespace internal {
 
+LIBC_INLINE double modf(double x, double *iptr) { return __nv_modf(x,iptr); }
 LIBC_INLINE double sin(double x) { return __nv_sin(x); }
 
 } // namespace internal