diff --git a/clang/lib/Headers/__clang_hip_libdevice_declares.h b/clang/lib/Headers/__clang_hip_libdevice_declares.h
--- a/clang/lib/Headers/__clang_hip_libdevice_declares.h
+++ b/clang/lib/Headers/__clang_hip_libdevice_declares.h
@@ -10,7 +10,9 @@
 #ifndef __CLANG_HIP_LIBDEVICE_DECLARES_H__
 #define __CLANG_HIP_LIBDEVICE_DECLARES_H__
 
+#ifdef __cplusplus
 extern "C" {
+#endif
 
 // BEGIN FLOAT
 __device__ __attribute__((const)) float __ocml_acos_f32(float);
@@ -316,7 +318,7 @@
 __device__ inline __2f16
 __llvm_amdgcn_rcp_2f16(__2f16 __x) // Not currently exposed by ROCDL.
 {
-  return __2f16{__llvm_amdgcn_rcp_f16(__x.x), __llvm_amdgcn_rcp_f16(__x.y)};
+  return (__2f16){__llvm_amdgcn_rcp_f16(__x.x), __llvm_amdgcn_rcp_f16(__x.y)};
 }
 __device__ __attribute__((const)) __2f16 __ocml_rint_2f16(__2f16);
 __device__ __attribute__((const)) __2f16 __ocml_rsqrt_2f16(__2f16);
@@ -325,6 +327,8 @@
 __device__ __attribute__((const)) __2f16 __ocml_trunc_2f16(__2f16);
 __device__ __attribute__((const)) __2f16 __ocml_pown_2f16(__2f16, __2i16);
 
+#ifdef __cplusplus
 } // extern "C"
+#endif
 
 #endif // __CLANG_HIP_LIBDEVICE_DECLARES_H__
diff --git a/clang/lib/Headers/__clang_hip_math.h b/clang/lib/Headers/__clang_hip_math.h
--- a/clang/lib/Headers/__clang_hip_math.h
+++ b/clang/lib/Headers/__clang_hip_math.h
@@ -95,8 +95,10 @@
 }
 
 // BEGIN FLOAT
+#ifdef __cplusplus
 __DEVICE__
 inline float abs(float __x) { return __ocml_fabs_f32(__x); }
+#endif
 __DEVICE__
 inline float acosf(float __x) { return __ocml_acos_f32(__x); }
 __DEVICE__
@@ -251,7 +253,7 @@
       uint32_t sign : 1;
     } bits;
 
-    static_assert(sizeof(float) == sizeof(ieee_float), "");
+    static_assert(sizeof(float) == sizeof(struct ieee_float), "");
   } __tmp;
 
   __tmp.bits.sign = 0u;
@@ -553,8 +555,10 @@
 // END FLOAT
 
 // BEGIN DOUBLE
+#ifdef __cplusplus
 __DEVICE__
 inline double abs(double __x) { return __ocml_fabs_f64(__x); }
+#endif
 __DEVICE__
 inline double acos(double __x) { return __ocml_acos_f64(__x); }
 __DEVICE__
@@ -712,7 +716,7 @@
       uint32_t exponent : 11;
       uint32_t sign : 1;
     } bits;
-    static_assert(sizeof(double) == sizeof(ieee_double), "");
+    static_assert(sizeof(double) == sizeof(struct ieee_double), "");
   } __tmp;
 
   __tmp.bits.sign = 0u;
@@ -1178,6 +1182,7 @@
   return std::max(__arg1, __arg2);
 }
 
+#ifdef __cplusplus
 __DEVICE__
 inline float pow(float __base, int __iexp) { return powif(__base, __iexp); }
 
@@ -1188,6 +1193,7 @@
 inline _Float16 pow(_Float16 __base, int __iexp) {
   return __ocml_pown_f16(__base, __iexp);
 }
+#endif
 
 #pragma pop_macro("__DEF_FUN1")
 #pragma pop_macro("__DEF_FUN2")