diff --git a/icu4c/source/common/icucfg.h.in b/icu4c/source/common/icucfg.h.in
index 59ed2744977..e564fa826a4 100644
--- a/icu4c/source/common/icucfg.h.in
+++ b/icu4c/source/common/icucfg.h.in
@@ -34,7 +34,7 @@
 #undef SIZEOF_WCHAR_T
 
 /* Define if you have the <inttypes.h> header file.  */
-#undef HAVE_INTTYPES_H
+#undef U_HAVE_INTTYPES_H
 
 /* Define if you have the cma library (-lcma).  */
 #undef HAVE_LIBCMA
diff --git a/icu4c/source/common/putil.c b/icu4c/source/common/putil.c
index 04cc6eca95f..01209a96291 100644
--- a/icu4c/source/common/putil.c
+++ b/icu4c/source/common/putil.c
@@ -86,7 +86,7 @@
 #   include <Script.h>
 #elif defined(AIX)
 #   include <sys/ldr.h>
-#elif defined(SOLARIS) || defined(LINUX)
+#elif defined(U_SOLARIS) || defined(U_LINUX)
 #   include <dlfcn.h>
 #   include <link.h>
 #elif defined(HPUX)
@@ -848,7 +848,7 @@ getLibraryPath(char *path, int size) {
 #   elif defined(OS390)
 #   elif defined(OS400)
 #   elif defined(XP_MAC)
-#   elif defined(SOLARIS)
+#   elif defined(U_SOLARIS)
         void *handle=dlopen(U_COMMON_LIBNAME, RTLD_LAZY); /* "libicu-uc.so" */
         if(handle!=NULL) {
             Link_map *p=NULL;
@@ -880,7 +880,7 @@ getLibraryPath(char *path, int size) {
             dlclose(handle);
             return length;
         }
-#   elif defined(LINUX)
+#   elif defined(U_LINUX)
 #   elif defined(AIX)
         void *handle=(void*)load(U_COMMON_LIBNAME, L_LIBPATH_EXEC, "."); /* "libicu-uc.a" */
         if(handle!=NULL) {
@@ -977,8 +977,8 @@ findLibraryPath(char *path, int size) {
 #       define LIB_FILENAME "libicuuc.a"
 #   elif defined(OS400)
 #   elif defined(XP_MAC)
-#   elif defined(SOLARIS)
-#   elif defined(LINUX)
+#   elif defined(U_SOLARIS)
+#   elif defined(U_LINUX)
 #       define LIB_PATH_VAR "LD_LIBRARY_PATH"
 #       define LIB_FILENAME "libicuuc.so"
 #   elif defined(AIX)
@@ -1480,7 +1480,7 @@ const char* uprv_getDefaultCodepage()
     {
         uprv_memset(codesetName, 0, 100);
     }
-#ifdef LINUX
+#ifdef U_LINUX
     if (nl_langinfo(_NL_CTYPE_CODESET_NAME) != NULL)
         uprv_strcpy(codesetName, nl_langinfo(_NL_CTYPE_CODESET_NAME));     
 #else
diff --git a/icu4c/source/common/ucnv_io.c b/icu4c/source/common/ucnv_io.c
index 67ba1a8d292..3b2e5ecb57f 100644
--- a/icu4c/source/common/ucnv_io.c
+++ b/icu4c/source/common/ucnv_io.c
@@ -136,28 +136,27 @@ isAlias(const char *alias, UErrorCode *pErrorCode) {
     }
 }
 
-/* compare lowercase str1 with mixed-case str2, ignoring case */
+/* compare lowercase str1 with mixed-case str2, both being charset names */
 static int
-strHalfCaseCmp(const char *str1, const char *str2) {
-    /* compare non-NULL strings lexically with lowercase */
+charsetNameCmp(const char *str1, const char *str2) {
     int rc;
     unsigned char c1, c2;
 
-    for(;;) {
-        c1=(unsigned char)*str1;
-        c2=(unsigned char)*str2;
-        if(c1==0) {
-            if(c2==0) {
+    for (;;) {
+        c1 = (unsigned char) *str1;
+        c2 = (unsigned char) *str2;
+        if (c1 == 0) {
+            if(c2 == 0) {
                 return 0;
             } else {
                 return -1;
             }
-        } else if(c2==0) {
+        } else if (c2 == 0) {
             return 1;
         } else {
             /* compare non-zero characters with lowercase */
-            rc=(int)c1-(int)(unsigned char)uprv_tolower(c2);
-            if(rc!=0) {
+            rc = (int) c1 - (int) (unsigned char) uprv_tolower(c2);
+            if(rc != 0) {
                 return rc;
             }
         }
@@ -192,7 +191,7 @@ findAlias(const char *alias) {
     start=0;
     while(start<limit-1) {
         i=(start+limit)/2;
-        if(strHalfCaseCmp(name, (const char *)aliasTable+p[i])<0) {
+        if(charsetNameCmp(name, (const char *)aliasTable+p[i])<0) {
             limit=i;
         } else {
             start=i;
@@ -200,7 +199,7 @@ findAlias(const char *alias) {
     }
 
     /* did we really find it? */
-    if(strHalfCaseCmp(name, (const char *)aliasTable+p[start])==0) {
+    if(charsetNameCmp(name, (const char *)aliasTable+p[start])==0) {
         limit=*(p-1);       /* aliasCount */
         p+=limit;           /* advance to the second column of the alias table */
         i=p[start];         /* converter index */
diff --git a/icu4c/source/common/udata.c b/icu4c/source/common/udata.c
index 7d79cade58c..d2668de1b07 100644
--- a/icu4c/source/common/udata.c
+++ b/icu4c/source/common/udata.c
@@ -209,7 +209,7 @@
 #   define MAP_IMPLEMENTATION MAP_WIN32
 
 /* ### Todo: auto detect mmap(). Until then, just add your platform here. */
-#elif defined(LINUX) || defined(POSIX) || defined(SOLARIS) || defined(AIX) || defined(HPUX) || defined(OS390) || defined(PTX)
+#elif defined(U_LINUX) || defined(POSIX) || defined(U_SOLARIS) || defined(AIX) || defined(HPUX) || defined(OS390) || defined(PTX)
     typedef size_t MemoryMap;
 
 #   define NO_MAP 0
diff --git a/icu4c/source/common/unicode/platform.h.in b/icu4c/source/common/unicode/platform.h.in
index 59f3d31653f..52349379c6f 100644
--- a/icu4c/source/common/unicode/platform.h.in
+++ b/icu4c/source/common/unicode/platform.h.in
@@ -22,8 +22,8 @@
 #endif
 
 /* Define whether inttypes.h is available */
-#ifndef HAVE_INTTYPES_H
-#define HAVE_INTTYPES_H @HAVE_INTTYPES_H@
+#ifndef U_HAVE_INTTYPES_H
+#define U_HAVE_INTTYPES_H @U_HAVE_INTTYPES_H@
 #endif
 
 /*
@@ -97,7 +97,7 @@
 
 /* If your platform does not have the <inttypes.h> header, you may
    need to edit the typedefs below. */
-#if HAVE_INTTYPES_H
+#if U_HAVE_INTTYPES_H
 #include <inttypes.h>
 #else
 #include <sys/types.h>
diff --git a/icu4c/source/common/unicode/pos2.h b/icu4c/source/common/unicode/pos2.h
index 5a1622044e8..606b495cf54 100644
--- a/icu4c/source/common/unicode/pos2.h
+++ b/icu4c/source/common/unicode/pos2.h
@@ -22,7 +22,7 @@
 #endif
 
 /* Define whether inttypes.h is available */
-#define HAVE_INTTYPES_H 0
+#define U_HAVE_INTTYPES_H 0
 
 /*
  * Define what support for C++ streams is available.
@@ -58,7 +58,7 @@
 
 /* If your platform does not have the <inttypes.h> header, you may
    need to edit the typedefs below. */
-#if HAVE_INTTYPES_H
+#if U_HAVE_INTTYPES_H
 #include <inttypes.h>
 #else
 
diff --git a/icu4c/source/common/unicode/pos400.h b/icu4c/source/common/unicode/pos400.h
index ccfe1cbf630..7b22b565e18 100644
--- a/icu4c/source/common/unicode/pos400.h
+++ b/icu4c/source/common/unicode/pos400.h
@@ -23,7 +23,7 @@
 #endif
 
 /* Define whether inttypes.h is available */
-#define HAVE_INTTYPES_H 0
+#define U_HAVE_INTTYPES_H 0
 
 /*
  * Define what support for C++ streams is available.
@@ -59,7 +59,7 @@
 
 /* If your platform does not have the <inttypes.h> header, you may
    need to edit the typedefs below. */
-#if HAVE_INTTYPES_H
+#if U_HAVE_INTTYPES_H
 #include <inttypes.h>
 #else
 
diff --git a/icu4c/source/common/unicode/pwin32.h b/icu4c/source/common/unicode/pwin32.h
index 898dbe62e15..50e839d453c 100644
--- a/icu4c/source/common/unicode/pwin32.h
+++ b/icu4c/source/common/unicode/pwin32.h
@@ -22,7 +22,7 @@
 #endif
 
 /* Define whether inttypes.h is available */
-#define HAVE_INTTYPES_H 0
+#define U_HAVE_INTTYPES_H 0
 
 /*
  * Define what support for C++ streams is available.
@@ -58,7 +58,7 @@
 
 /* If your platform does not have the <inttypes.h> header, you may
    need to edit the typedefs below. */
-#if HAVE_INTTYPES_H
+#if U_HAVE_INTTYPES_H
 #include <inttypes.h>
 #else
 
diff --git a/icu4c/source/config/Makefile.inc.in b/icu4c/source/config/Makefile.inc.in
index b385e93f3a4..28296ebc4cd 100644
--- a/icu4c/source/config/Makefile.inc.in
+++ b/icu4c/source/config/Makefile.inc.in
@@ -2,7 +2,7 @@
 #******************************************************************************
 #   Copyright (C) 1999, International Business Machines
 #   Corporation and others.  All Rights Reserved.
-# $Revision: 1.2 $
+# $Revision: 1.3 $
 #******************************************************************************
 # This Makefile is designed to be included into projects which make use
 # of the ICU.
@@ -52,7 +52,7 @@ host_vendor=@host_vendor@
 host_os=@host_os@
 LIB_M=@LIB_M@
 CPP=@CPP@
-HAVE_INTTYPES_H=@HAVE_INTTYPES_H@
+U_HAVE_INTTYPES_H=@U_HAVE_INTTYPES_H@
 U_IS_BIG_ENDIAN=@U_IS_BIG_ENDIAN@
 HAVE_INT8_T=@HAVE_INT8_T@
 HAVE_UINT8_T=@HAVE_UINT8_T@
diff --git a/icu4c/source/configure b/icu4c/source/configure
index c501240af99..cf616e80163 100755
--- a/icu4c/source/configure
+++ b/icu4c/source/configure
@@ -2068,9 +2068,9 @@ fi
 done
 
 if test $ac_cv_header_inttypes_h = no; then
-HAVE_INTTYPES_H=0
+U_HAVE_INTTYPES_H=0
 else
-HAVE_INTTYPES_H=1
+U_HAVE_INTTYPES_H=1
 fi
 
 
@@ -2908,16 +2908,16 @@ else
 fi
 
 case "${host}" in
-	*-*-solaris*) 	platform=SOLARIS ;;
-	*-*-linux*) 	platform=LINUX ;;
-	*-*-freebsd*) 	platform=LINUX ;;
+	*-*-solaris*) 	platform=U_SOLARIS ;;
+	*-*-linux*) 	platform=U_LINUX ;;
+	*-*-freebsd*) 	platform=U_LINUX ;;
 	*-*-aix*) 	platform=AIX ;;
 	*-*-hpux*) 	platform=HPUX ;;
 	*-*-irix*)      platform=IRIX ;;
 	*-*-os390*)	platform=OS390 ;;
 	*-*-os400*)	platform=OS400 ;;
-	*-apple-rhapsody*)	platform=RHAPSODY ;;
-	*) 		platform=UNKNOWN ;;
+	*-apple-rhapsody*)	platform=U_RHAPSODY ;;
+	*) 		platform=U_UNKNOWN_PLATFORM ;;
 esac
 
 host_frag=$icu_cv_host_frag
@@ -3154,7 +3154,7 @@ s%@THREADS_FALSE@%$THREADS_FALSE%g
 s%@ICU_USE_THREADS@%$ICU_USE_THREADS%g
 s%@HAVE_DLOPEN@%$HAVE_DLOPEN%g
 s%@CPP@%$CPP%g
-s%@HAVE_INTTYPES_H@%$HAVE_INTTYPES_H%g
+s%@U_HAVE_INTTYPES_H@%$U_HAVE_INTTYPES_H%g
 s%@CXXCPP@%$CXXCPP%g
 s%@U_IOSTREAM_SOURCE@%$U_IOSTREAM_SOURCE%g
 s%@U_IS_BIG_ENDIAN@%$U_IS_BIG_ENDIAN%g
diff --git a/icu4c/source/configure.in b/icu4c/source/configure.in
index 3d3aa1c2b0b..a1ad5a73434 100644
--- a/icu4c/source/configure.in
+++ b/icu4c/source/configure.in
@@ -197,11 +197,11 @@ AC_SUBST(HAVE_DLOPEN)
 dnl Checks for header files
 AC_CHECK_HEADERS(inttypes.h)
 if test $ac_cv_header_inttypes_h = no; then
-HAVE_INTTYPES_H=0
+U_HAVE_INTTYPES_H=0
 else
-HAVE_INTTYPES_H=1
+U_HAVE_INTTYPES_H=1
 fi
-AC_SUBST(HAVE_INTTYPES_H)
+AC_SUBST(U_HAVE_INTTYPES_H)
 
 if test x$U_IOSTREAM_SOURCE = x
 then
@@ -370,17 +370,17 @@ ICU_CONDITIONAL(SAMPLES, test "$samples" = true)
 
 dnl Platform-specific Makefile setup
 case "${host}" in
-	*-*-solaris*) 	platform=SOLARIS ;;
-	*-*-linux*) 	platform=LINUX ;;
-	*-*-freebsd*) 	platform=LINUX ;;
+	*-*-solaris*) 	platform=U_SOLARIS ;;
+	*-*-linux*) 	platform=U_LINUX ;;
+	*-*-freebsd*) 	platform=U_LINUX ;;
 	*-*-aix*) 	platform=AIX ;;
 	*-sequent-*)	platform=PTX ;;
 	*-*-hpux*) 	platform=HPUX ;;
 	*-*-irix*)      platform=IRIX ;;
 	*-*-os390*)	platform=OS390 ;;
 	*-*-os400*)	platform=OS400 ;;
-	*-apple-rhapsody*)	platform=RHAPSODY ;;
-	*) 		platform=UNKNOWN ;;
+	*-apple-rhapsody*)	platform=U_RHAPSODY ;;
+	*) 		platform=U_UNKNOWN_PLATFORM ;;
 esac
 AC_SUBST(platform)
 host_frag=$icu_cv_host_frag
diff --git a/icu4c/source/test/cintltst/cintltst.c b/icu4c/source/test/cintltst/cintltst.c
index a142b189d63..a096564cbbc 100644
--- a/icu4c/source/test/cintltst/cintltst.c
+++ b/icu4c/source/test/cintltst/cintltst.c
@@ -134,7 +134,7 @@ ctest_getTestDirectory()
 {
     if (_testDirectory == NULL) 
     {
-#if defined(_AIX) || defined(SOLARIS) || defined(LINUX) || defined(HPUX) || defined(POSIX) || defined(OS390)
+#if defined(_AIX) || defined(U_SOLARIS) || defined(U_LINUX) || defined(HPUX) || defined(POSIX) || defined(OS390)
         ctest_setTestDirectory("source|test|testdata|");
 #else
         ctest_setTestDirectory("icu|source|test|testdata|");
diff --git a/icu4c/source/test/intltest/intltest.cpp b/icu4c/source/test/intltest/intltest.cpp
index 6dc83bcdc37..ce33a122bf0 100644
--- a/icu4c/source/test/intltest/intltest.cpp
+++ b/icu4c/source/test/intltest/intltest.cpp
@@ -376,7 +376,7 @@ IntlTest::pathnameInContext( char* fullname, int32_t maxsize, const char* relPat
             mainDirBuffer[0]='\0';
         }
         mainDir=mainDirBuffer;
-    #elif defined(_AIX) || defined(SOLARIS) || defined(LINUX) || defined(HPUX) || defined(POSIX) || defined(OS390)
+    #elif defined(_AIX) || defined(U_SOLARIS) || defined(U_LINUX) || defined(HPUX) || defined(POSIX) || defined(OS390)
         char mainDirBuffer[200];
         strcpy(mainDirBuffer, u_getDataDirectory());
         strcat(mainDirBuffer, "/../");
@@ -402,7 +402,7 @@ IntlTest::pathnameInContext( char* fullname, int32_t maxsize, const char* relPat
         }
         mainDir=mainDirBuffer;
         sepChar = '\\';
-    #elif defined(_AIX) || defined(SOLARIS) || defined(LINUX) || defined(HPUX) || defined(OS390)
+    #elif defined(_AIX) || defined(SOLARIS) || defined(U_LINUX) || defined(HPUX) || defined(OS390)
         mainDir = getenv("HOME");
         sepChar = '/';
     #elif defined(XP_MAC)
@@ -443,7 +443,7 @@ IntlTest::getTestDirectory()
 {
        if (_testDirectory == NULL) 
     {
-#if defined(_AIX) || defined(SOLARIS) || defined(LINUX) || defined(HPUX) || defined(POSIX) || defined(OS390)
+#if defined(_AIX) || defined(SOLARIS) || defined(U_LINUX) || defined(HPUX) || defined(POSIX) || defined(OS390)
       setTestDirectory("source|test|testdata|");
 #else
       setTestDirectory("icu|source|test|testdata|");
diff --git a/icu4c/source/test/intltest/tsmthred.cpp b/icu4c/source/test/intltest/tsmthred.cpp
index 1a6ad5a0c6f..04377f42665 100644
--- a/icu4c/source/test/intltest/tsmthred.cpp
+++ b/icu4c/source/test/intltest/tsmthred.cpp
@@ -16,7 +16,7 @@
 #define POSIX 1
 #endif
 
-#if defined(POSIX)||defined(SOLARIS)||defined(AIX)||defined(HPUX)
+#if defined(POSIX)||defined(U_SOLARIS)||defined(AIX)||defined(HPUX)
 #define HAVE_IMP
 
 #include <pthread.h>
@@ -180,7 +180,7 @@ SimpleThread::sleep(int32_t millis)
 #endif
 
 
-#if defined(POSIX)||defined(SOLARIS)||defined(AIX)||defined(HPUX)
+#if defined(POSIX)||defined(U_SOLARIS)||defined(AIX)||defined(HPUX)
 #define HAVE_IMP
 
 struct PosixThreadImplementation
@@ -227,7 +227,7 @@ void SimpleThread::start()
 
 void SimpleThread::sleep(int32_t millis)
 {
-#ifdef SOLARIS
+#ifdef U_SOLARIS
    sigignore(SIGALRM);
 #endif
 
diff --git a/icu4c/source/test/intltest/tsmutex.cpp b/icu4c/source/test/intltest/tsmutex.cpp
index 9785b3fd575..fd8bafec89b 100644
--- a/icu4c/source/test/intltest/tsmutex.cpp
+++ b/icu4c/source/test/intltest/tsmutex.cpp
@@ -8,7 +8,7 @@
 #include <stdio.h>
 #include <string.h>
 
-#ifdef SOLARIS
+#ifdef U_SOLARIS
 #include <signal.h>
 #endif
 
diff --git a/icu4c/source/tools/icupkg.inc.in b/icu4c/source/tools/icupkg.inc.in
index e9ad9687667..a8edeaf3e7e 100644
--- a/icu4c/source/tools/icupkg.inc.in
+++ b/icu4c/source/tools/icupkg.inc.in
@@ -54,7 +54,7 @@ host_vendor=@host_vendor@
 host_os=@host_os@
 LIB_M=@LIB_M@
 CPP=@CPP@
-HAVE_INTTYPES_H=@HAVE_INTTYPES_H@
+U_HAVE_INTTYPES_H=@U_HAVE_INTTYPES_H@
 U_IS_BIG_ENDIAN=@U_IS_BIG_ENDIAN@
 HAVE_INT8_T=@HAVE_INT8_T@
 HAVE_UINT8_T=@HAVE_UINT8_T@
@@ -94,6 +94,6 @@ ifeq ($(strip $(PLATFORM)),HPUX)
   TOOL=env LD_LIBRARY_PATH=../source/common:../source/i18n:../source/tools/toolutil
 endif
 
-ifeq ($(strip $(PLATFORM)),LINUX)
+ifeq ($(strip $(PLATFORM)),U_LINUX)
   TOOL=env LD_LIBRARY_PATH=../source/common:../source/i18n:../source/tools/toolutil
 endif