diff --git a/icu4c/source/test/cintltst/ccapitst.c b/icu4c/source/test/cintltst/ccapitst.c
index 476495a94b8..6642e18809d 100644
--- a/icu4c/source/test/cintltst/ccapitst.c
+++ b/icu4c/source/test/cintltst/ccapitst.c
@@ -973,7 +973,7 @@ static void TestConvert()
     free((void*)my_ucs_file_buffer);
 }
 
-void WriteToFile(const UChar *a, FILE *myfile)
+static void WriteToFile(const UChar *a, FILE *myfile)
 {
     uint32_t  size    = u_strlen(a);
     uint16_t  i       = 0;
@@ -988,7 +988,7 @@ void WriteToFile(const UChar *a, FILE *myfile)
     }
 }
 
-int32_t strCaseIcmp(const char* a1, const char * a2)
+static int32_t strCaseIcmp(const char* a1, const char * a2)
 {
     int32_t i=0, ret=0;
     while(a1[i]&&a2[i]) 
@@ -999,13 +999,13 @@ int32_t strCaseIcmp(const char* a1, const char * a2)
     return ret;
 }
 
-UConverterFromUCallback otherUnicodeAction(UConverterFromUCallback MIA)
+static UConverterFromUCallback otherUnicodeAction(UConverterFromUCallback MIA)
 {
     return (MIA==(UConverterFromUCallback)UCNV_FROM_U_CALLBACK_STOP)?(UConverterFromUCallback)UCNV_FROM_U_CALLBACK_SUBSTITUTE:(UConverterFromUCallback)UCNV_FROM_U_CALLBACK_STOP;
 }
 
 
-UConverterToUCallback otherCharAction(UConverterToUCallback MIA)
+static UConverterToUCallback otherCharAction(UConverterToUCallback MIA)
 {
     return (MIA==(UConverterToUCallback)UCNV_TO_U_CALLBACK_STOP)?(UConverterToUCallback)UCNV_TO_U_CALLBACK_SUBSTITUTE:(UConverterToUCallback)UCNV_TO_U_CALLBACK_STOP;
 }
diff --git a/icu4c/source/test/cintltst/cg7coll.c b/icu4c/source/test/cintltst/cg7coll.c
index 4f69301dfe1..89b9274491a 100644
--- a/icu4c/source/test/cintltst/cg7coll.c
+++ b/icu4c/source/test/cintltst/cg7coll.c
@@ -117,7 +117,8 @@ const static int32_t results[TESTLOCALES][TOTALTESTSET] = {
     /* analogous to Japanese rules " & aa ; a- & ee ; e- & ii ; i- & oo ; o- & uu ; u- " */  /* loop to TOTALTESTSET */
     { 19, 22, 21, 23, 24, 25, 12, 13, 9, 0, 17, 16, 26, 27, 28, 15, 18, 14, 1, 11, 2, 3, 4, 5, 20, 6, 8, 10, 7, 29 }
 };
-UChar* 
+
+static UChar* 
 my_strncpy(UChar     *dst, 
      const UChar     *src, 
      int32_t     n) 
@@ -131,7 +132,7 @@ my_strncpy(UChar     *dst,
   return anchor;
 }
 
-UChar* 
+static UChar* 
 my_strcat(UChar     *dst, 
      const UChar     *src,
      int32_t n)
@@ -147,6 +148,7 @@ my_strcat(UChar     *dst,
   
   return anchor;
 }
+
 void addRuleBasedCollTest(TestNode** root)
 {
     addTest(root, &TestG7Locales, "tscoll/cg7coll/TestG7Locales");
@@ -157,7 +159,8 @@ void addRuleBasedCollTest(TestNode** root)
 
     
 }
-void doTest(UCollator *myCollation, const UChar source[], const UChar target[], UCollationResult result)
+
+static void doTest(UCollator *myCollation, const UChar source[], const UChar target[], UCollationResult result)
 {
     int32_t sortklen1, sortklen2, sortklenmax, sortklenmin;
     int32_t temp;
@@ -188,7 +191,7 @@ void doTest(UCollator *myCollation, const UChar source[], const UChar target[],
     free(sortKey2);
 }
 
-void TestG7Locales()
+static void TestG7Locales()
 {
     UCollator *myCollation, *tblColl1;
     UErrorCode status = U_ZERO_ERROR;
@@ -235,7 +238,7 @@ void TestG7Locales()
     }
 }
 
-void TestDemo1()
+static void TestDemo1()
 {
     UCollator *col, *myCollation;
     const UChar *baseRules;
@@ -281,7 +284,8 @@ void TestDemo1()
     free(temp);
     free(newRules);
 }
-void TestDemo2()
+
+static void TestDemo2()
 {
     UCollator *col, *myCollation;
     UErrorCode status = U_ZERO_ERROR;
@@ -326,7 +330,7 @@ void TestDemo2()
     
 }
 
-void TestDemo3()
+static void TestDemo3()
 {
     UCollator *col, *myCollation;
     UErrorCode status = U_ZERO_ERROR;
@@ -372,7 +376,7 @@ void TestDemo3()
     
 }
 
-void TestDemo4()
+static void TestDemo4()
 {
     UCollator *col, *myCollation;
     UErrorCode status = U_ZERO_ERROR;
diff --git a/icu4c/source/test/cintltst/cg7coll.h b/icu4c/source/test/cintltst/cg7coll.h
index fdf4fc23b88..60aeb428a84 100644
--- a/icu4c/source/test/cintltst/cg7coll.h
+++ b/icu4c/source/test/cintltst/cg7coll.h
@@ -47,23 +47,23 @@
 
         
     /* main test routine, tests comparisons for a set of strings against sets of expected results */
-   static  void doTest(UCollator *myCollation, const UChar* source, const UChar* target, UCollationResult result);
+    static void doTest(UCollator *myCollation, const UChar* source, const UChar* target, UCollationResult result);
     
     /* perform test for G7 locales */
-    void TestG7Locales(void);
+    static void TestG7Locales(void);
 
     /* perform test with added rules " & Z < p, P" */
-    void TestDemo1(void);
+    static void TestDemo1(void);
 
     /* perorm test with added rules "& C < ch , cH, Ch, CH" */
-    void TestDemo2(void);
+    static void TestDemo2(void);
 
     /* perform test with added rules  */
     /* "& Question'-'mark ; '?' & Hash'-'mark ; '#' & Ampersand ; '&'" */
-    void TestDemo3(void);
+    static void TestDemo3(void);
 
     /* perform test with added rules  */
     /* " & aa ; a'-' & ee ; e'-' & ii ; i'-' & oo ; o'-' & uu ; u'-' " */
-    void TestDemo4(void);
+    static void TestDemo4(void);
 
 #endif
diff --git a/icu4c/source/test/cintltst/chashtst.c b/icu4c/source/test/cintltst/chashtst.c
index 920e56a721f..4f35e9e058a 100644
--- a/icu4c/source/test/cintltst/chashtst.c
+++ b/icu4c/source/test/cintltst/chashtst.c
@@ -22,20 +22,20 @@
 static void TestBasic(void);
 static void TestOtherAPI(void);
 
-int32_t hashChars(const void* key);
+static int32_t hashChars(const void* key);
 
-UBool isEqualChars(const void* key1, const void* key2);
+static UBool isEqualChars(const void* key1, const void* key2);
 
 static void _put(UHashtable* hash,
                  const char* key,
                  int32_t value,
                  int32_t expectedOldValue);
 
-void _get(UHashtable* hash,
+static void _get(UHashtable* hash,
           const char* key,
           int32_t expectedValue);
 
-void _remove(UHashtable* hash,
+static void _remove(UHashtable* hash,
              const char* key,
              int32_t expectedValue);
 
@@ -54,7 +54,7 @@ void addHashtableTest(TestNode** root) {
  * Test Functions
  *********************************************************************/
 
-void TestBasic(void) {
+static void TestBasic(void) {
     const char one[4] =   {0x6F, 0x6E, 0x65, 0}; /* "one" */
     const char one2[4] =  {0x6F, 0x6E, 0x65, 0}; /* Get around compiler optimizations */
     const char two[4] =   {0x74, 0x77, 0x6F, 0}; /* "two" */
@@ -107,7 +107,8 @@ void TestBasic(void) {
     uhash_close(hash);
 
 }
-void TestOtherAPI(void){
+
+static void TestOtherAPI(void){
     
     UErrorCode status = U_ZERO_ERROR;
     UHashtable *hash;
@@ -236,7 +237,7 @@ UBool isEqualChars(const void* key1, const void* key2) {
  * Wrapper Functions
  *********************************************************************/
 
-void _put(UHashtable* hash,
+static void _put(UHashtable* hash,
           const char* key,
           int32_t value,
           int32_t expectedOldValue) {
@@ -255,7 +256,7 @@ void _put(UHashtable* hash,
     }
 }
 
-void _get(UHashtable* hash,
+static void _get(UHashtable* hash,
           const char* key,
           int32_t expectedValue) {
     UErrorCode status = U_ZERO_ERROR;
@@ -272,7 +273,7 @@ void _get(UHashtable* hash,
     }
 }
 
-void _remove(UHashtable* hash,
+static void _remove(UHashtable* hash,
              const char* key,
              int32_t expectedValue) {
     int32_t value = (int32_t) uhash_remove(hash, key);
diff --git a/icu4c/source/test/cintltst/cucdtst.c b/icu4c/source/test/cintltst/cucdtst.c
index cbd08e20135..56b1c1d846c 100644
--- a/icu4c/source/test/cintltst/cucdtst.c
+++ b/icu4c/source/test/cintltst/cucdtst.c
@@ -76,6 +76,7 @@ const int32_t tagValues[] =
     /* Pi */ U_INITIAL_PUNCTUATION,
     /* Pf */ U_FINAL_PUNCTUATION
     };
+
 const char dirStrings[][5] = {
     "L",
     "R",
@@ -357,8 +358,9 @@ static void TestControlPrint()
         }
     }
 }
+
 /* u_isJavaIDStart, u_isJavaIDPart, u_isIDStart(), u_isIDPart(), u_isIDIgnorable()*/
-void TestIdentifier()
+static void TestIdentifier()
 {
     const UChar sampleJavaIDStart[] = {0x0071, 0x00e4, 0x005f};
     const UChar sampleNonJavaIDStart[] = {0x0020, 0x2030, 0x0082};
@@ -568,7 +570,7 @@ static int32_t MakeProp(char* str)
     return result;
 }
 
-int32_t MakeDir(char* str) 
+static int32_t MakeDir(char* str) 
 {
     int32_t pos = 0;
     for (pos = 0; pos < 19; pos++) {
@@ -592,7 +594,7 @@ static const char* raw[3][4] = {
     {   "English_United States", "French_France", "Croatian_Croatia", "English_United States"}
 };
    
-void setUpDataTable()
+U_CFUNC void setUpDataTable()
 {
     int32_t i,j;
     if(dataTable == NULL) {
@@ -625,7 +627,7 @@ U_CFUNC void cleanUpDataTable()
 }
 
 /*Tests  for u_strcat(),u_strcmp(), u_strlen(), u_strcpy(),u_strncat(),u_strncmp(),u_strncpy, u_uastrcpy(),u_austrcpy(), u_uastrncpy(); */
-void TestStringFunctions()
+static void TestStringFunctions()
 {
    
     int32_t i,j,k;
diff --git a/icu4c/source/test/cintltst/ncnvfbts.c b/icu4c/source/test/cintltst/ncnvfbts.c
index 7472010576f..43cae739150 100644
--- a/icu4c/source/test/cintltst/ncnvfbts.c
+++ b/icu4c/source/test/cintltst/ncnvfbts.c
@@ -439,7 +439,7 @@ static UBool testConvertToUnicode( const uint8_t *source, int sourcelen, const U
 
 
 
-void TestConvertFallBackWithBufferSizes(int32_t outsize, int32_t insize ) 
+static void TestConvertFallBackWithBufferSizes(int32_t outsize, int32_t insize ) 
 {
 
     UChar    SBCSText[] = 
diff --git a/icu4c/source/test/cintltst/ucmptst.c b/icu4c/source/test/cintltst/ucmptst.c
index 572dc45b063..129e3356013 100644
--- a/icu4c/source/test/cintltst/ucmptst.c
+++ b/icu4c/source/test/cintltst/ucmptst.c
@@ -38,7 +38,7 @@ addCompactArrayTest(TestNode** root)
  
 }
 
-void TestUCMP16API(){
+static void TestUCMP16API(){
      int16_t newValues[]={
         0x00, 0x01, 0x02, 0x03, 0x04, 
         0x05, 0x06, 0x07, 0x08, 0x09, 
@@ -183,7 +183,7 @@ void TestUCMP16API(){
 
 }
 
-void TestUCMP8API(){
+static void TestUCMP8API(){
     CompactByteArray* ucmp8Array=NULL;
     CompactByteArray* ucmp8Array1=NULL;
     CompactByteArray* ucmp8Array2=NULL;
@@ -277,7 +277,7 @@ void TestUCMP8API(){
     ucmp8_close(ucmp8Array2);
 }
 
-void TestUCMP32API(){
+static void TestUCMP32API(){
     CompactIntArray* ucmp32Array=NULL;
    
     int32_t i=0;