Index: cmake/modules/HandleLLVMOptions.cmake
===================================================================
--- cmake/modules/HandleLLVMOptions.cmake
+++ cmake/modules/HandleLLVMOptions.cmake
@@ -580,6 +580,8 @@
 
   # Enable -Wstring-conversion to catch misuse of string literals.
   add_flag_if_supported("-Wstring-conversion" STRING_CONVERSION_FLAG)
+  # Enable -Wstrict-prototypes to catch incorrectly declared functions in C.
+  add_flag_if_supported("-Wstrict-prototypes" STRICT_PROTOTYPES_FLAG)
 endif (LLVM_ENABLE_WARNINGS AND (LLVM_COMPILER_IS_GCC_COMPATIBLE OR CLANG_CL))
 
 if (LLVM_COMPILER_IS_GCC_COMPATIBLE AND NOT LLVM_ENABLE_WARNINGS)
Index: projects/compiler-rt/lib/profile/GCDAProfiling.c
===================================================================
--- projects/compiler-rt/lib/profile/GCDAProfiling.c
+++ projects/compiler-rt/lib/profile/GCDAProfiling.c
@@ -92,7 +92,7 @@
 /*
  * A list of functions to write out the data.
  */
-typedef void (*writeout_fn)();
+typedef void (*writeout_fn)(void);
 
 struct writeout_fn_node {
   writeout_fn fn;
@@ -105,7 +105,7 @@
 /*
  *  A list of flush functions that our __gcov_flush() function should call.
  */
-typedef void (*flush_fn)();
+typedef void (*flush_fn)(void);
 
 struct flush_fn_node {
   flush_fn fn;
Index: projects/compiler-rt/lib/profile/InstrProfiling.h
===================================================================
--- projects/compiler-rt/lib/profile/InstrProfiling.h
+++ projects/compiler-rt/lib/profile/InstrProfiling.h
@@ -63,8 +63,8 @@
 const char *__llvm_profile_end_names(void);
 uint64_t *__llvm_profile_begin_counters(void);
 uint64_t *__llvm_profile_end_counters(void);
-ValueProfNode *__llvm_profile_begin_vnodes();
-ValueProfNode *__llvm_profile_end_vnodes();
+ValueProfNode *__llvm_profile_begin_vnodes(void);
+ValueProfNode *__llvm_profile_end_vnodes(void);
 
 /*!
  * \brief Clear profile counters to zero.
@@ -164,7 +164,7 @@
  * merge mode is turned on for instrumented programs with shared libs).
  * Side-effect: this API call will invoke malloc with dynamic memory allocation.
  */
-const char *__llvm_profile_get_path_prefix();
+const char *__llvm_profile_get_path_prefix(void);
 
 /*! \brief Get the magic token for the file format. */
 uint64_t __llvm_profile_get_magic(void);
Index: projects/compiler-rt/lib/profile/InstrProfilingFile.c
===================================================================
--- projects/compiler-rt/lib/profile/InstrProfilingFile.c
+++ projects/compiler-rt/lib/profile/InstrProfilingFile.c
@@ -86,7 +86,7 @@
                                                    0, 0, 0, PNS_unknown};
 
 int getpid(void);
-static int getCurFilenameLength();
+static int getCurFilenameLength(void);
 static const char *getCurFilename(char *FilenameBuf);
 static unsigned doMerging() { return lprofCurFilename.MergePoolSize; }
 
Index: projects/compiler-rt/lib/profile/InstrProfilingInternal.h
===================================================================
--- projects/compiler-rt/lib/profile/InstrProfilingInternal.h
+++ projects/compiler-rt/lib/profile/InstrProfilingInternal.h
@@ -155,27 +155,27 @@
 void lprofMergeValueProfData(struct ValueProfData *SrcValueProfData,
                              __llvm_profile_data *DstData);
 
-VPDataReaderType *lprofGetVPDataReader();
+VPDataReaderType *lprofGetVPDataReader(void);
 
 /* Internal interface used by test to reset the max number of 
  * tracked values per value site to be \p MaxVals.
  */
 void lprofSetMaxValsPerSite(uint32_t MaxVals);
-void lprofSetupValueProfiler();
+void lprofSetupValueProfiler(void);
 
 /* Return the profile header 'signature' value associated with the current
  * executable or shared library. The signature value can be used to for
  * a profile name that is unique to this load module so that it does not
  * collide with profiles from other binaries. It also allows shared libraries
  * to dump merged profile data into its own profile file. */
-uint64_t lprofGetLoadModuleSignature();
+uint64_t lprofGetLoadModuleSignature(void);
 
 /* 
  * Return non zero value if the profile data has already been
  * dumped to the file.
  */
-unsigned lprofProfileDumped();
-void lprofSetProfileDumped();
+unsigned lprofProfileDumped(void);
+void lprofSetProfileDumped(void);
 
 COMPILER_RT_VISIBILITY extern void (*FreeHook)(void *);
 COMPILER_RT_VISIBILITY extern uint8_t *DynamicBufferIOBuffer;
Index: projects/compiler-rt/lib/profile/InstrProfilingUtil.h
===================================================================
--- projects/compiler-rt/lib/profile/InstrProfilingUtil.h
+++ projects/compiler-rt/lib/profile/InstrProfilingUtil.h
@@ -54,9 +54,9 @@
 /* Temporarily suspend SIGKILL. Return value of 1 means a restore is needed.
  * Other return values mean no restore is needed.
  */
-int lprofSuspendSigKill();
+int lprofSuspendSigKill(void);
 
 /* Restore previously suspended SIGKILL. */
-void lprofRestoreSigKill();
+void lprofRestoreSigKill(void);
 
 #endif /* PROFILE_INSTRPROFILINGUTIL_H */
Index: projects/libunwind/src/config.h
===================================================================
--- projects/libunwind/src/config.h
+++ projects/libunwind/src/config.h
@@ -119,9 +119,9 @@
   #ifdef __cplusplus
     extern "C" {
   #endif
-    extern  bool logAPIs();
-    extern  bool logUnwinding();
-    extern  bool logDWARF();
+    extern  bool logAPIs(void);
+    extern  bool logUnwinding(void);
+    extern  bool logDWARF(void);
   #ifdef __cplusplus
     }
   #endif
Index: projects/libunwind/src/unwind_ext.h
===================================================================
--- projects/libunwind/src/unwind_ext.h
+++ projects/libunwind/src/unwind_ext.h
@@ -23,7 +23,7 @@
 // implemented elsewhere.
 
 extern struct _Unwind_FunctionContext *
-__Unwind_SjLj_GetTopOfFunctionStack();
+__Unwind_SjLj_GetTopOfFunctionStack(void);
 
 extern void
 __Unwind_SjLj_SetTopOfFunctionStack(struct _Unwind_FunctionContext *fc);