diff --git a/MultiSource/Applications/ClamAV/clamscan_clamscan.c b/MultiSource/Applications/ClamAV/clamscan_clamscan.c
--- a/MultiSource/Applications/ClamAV/clamscan_clamscan.c
+++ b/MultiSource/Applications/ClamAV/clamscan_clamscan.c
@@ -60,7 +60,7 @@
 	int ds, dms, ret;
 	double mb;
 	struct timeval t1, t2;
-#ifndef C_WINDOWS
+#if !defined(C_WINDOWS) && (!defined(_AIX) || defined(_ALL_SOURCE))
 	struct timezone tz;
 #endif
 	struct optstruct *opt;
@@ -208,7 +208,9 @@
 	_CrtSetReportMode(_CRT_ERROR, _CRTDBG_MODE_FILE);
 	_CrtSetReportFile(_CRT_ERROR, _CRTDBG_FILE_STDERR);
     }
-#endif	
+#endif
+#endif
+#if defined(C_WINDOWS) || (defined(_AIX) && !defined(_ALL_SOURCE))
     gettimeofday(&t1, NULL);
 #else
     gettimeofday(&t1, &tz);
@@ -217,7 +219,7 @@
     ret = scanmanager(opt);
 
     if(!opt_check(opt, "disable-summary") && !opt_check(opt, "no-summary")) {
-#ifdef C_WINDOWS
+#if defined(C_WINDOWS) || (defined(_AIX) && !defined(_ALL_SOURCE))
 	gettimeofday(&t2, NULL);
 #else
 	gettimeofday(&t2, &tz);
diff --git a/MultiSource/Benchmarks/MallocBench/espresso/port.h b/MultiSource/Benchmarks/MallocBench/espresso/port.h
--- a/MultiSource/Benchmarks/MallocBench/espresso/port.h
+++ b/MultiSource/Benchmarks/MallocBench/espresso/port.h
@@ -5,19 +5,6 @@
 #define volatile
 #endif
 
-#ifdef _IBMR2
-#define _BSD
-#ifndef _POSIX_SOURCE
-#define _POSIX_SOURCE		/* Argh!  IBM strikes again */
-#endif
-#ifndef _ALL_SOURCE
-#define _ALL_SOURCE		/* Argh!  IBM strikes again */
-#endif
-#ifndef _ANSI_C_SOURCE
-#define _ANSI_C_SOURCE		/* Argh!  IBM strikes again */
-#endif
-#endif
-
 /*
  * int32 should be defined as the most economical sized integer capable of
  * holding a 32 bit quantity
diff --git a/MultiSource/Benchmarks/MallocBench/gs/gp_unix.c b/MultiSource/Benchmarks/MallocBench/gs/gp_unix.c
--- a/MultiSource/Benchmarks/MallocBench/gs/gp_unix.c
+++ b/MultiSource/Benchmarks/MallocBench/gs/gp_unix.c
@@ -23,6 +23,12 @@
 #include "gx.h"
 #include <time.h>
 #include <sys/time.h>
+#if _AIX && !defined(_ALL_SOURCE)
+struct timezone {
+	int tz_minuteswest;
+	int tz_dsttime;
+};
+#endif
 
 /* Do platform-dependent initialization */
 void
diff --git a/MultiSource/Benchmarks/MiBench/consumer-lame/formatBitstream.h b/MultiSource/Benchmarks/MiBench/consumer-lame/formatBitstream.h
--- a/MultiSource/Benchmarks/MiBench/consumer-lame/formatBitstream.h
+++ b/MultiSource/Benchmarks/MiBench/consumer-lame/formatBitstream.h
@@ -24,6 +24,11 @@
 #define MAX_GRANULES 2
 #endif
 
+#if _AIX && !defined(_ALL_SOURCE)
+typedef unsigned int   u_int;
+typedef unsigned short u_short;
+#endif
+
 /*
   This is the prototype for the function pointer you must
   provide to write bits to the bitstream. It should write
diff --git a/MultiSource/Benchmarks/MiBench/consumer-lame/util.h b/MultiSource/Benchmarks/MiBench/consumer-lame/util.h
--- a/MultiSource/Benchmarks/MiBench/consumer-lame/util.h
+++ b/MultiSource/Benchmarks/MiBench/consumer-lame/util.h
@@ -125,6 +125,13 @@
 
 #include "l3side.h"
 
+#if _AIX && !defined(_ALL_SOURCE)
+typedef unsigned char  u_char;
+typedef unsigned int   u_int;
+typedef unsigned short u_short;
+typedef unsigned long  u_long;
+#endif
+
 /***********************************************************************
 *
 *  Global Variable External Declarations
diff --git a/MultiSource/Benchmarks/MiBench/office-ispell/term.c b/MultiSource/Benchmarks/MiBench/office-ispell/term.c
--- a/MultiSource/Benchmarks/MiBench/office-ispell/term.c
+++ b/MultiSource/Benchmarks/MiBench/office-ispell/term.c
@@ -47,6 +47,10 @@
 
 /*
  * $Log$
+ *
+ * Revision 1.2  2020/03/23 12:59:43  stevenwan
+ * Add IBM AIX workaround.
+ *
  * Revision 1.1  2007/01/09 23:57:18  lattner
  * initial recheckin of mibench
  *
@@ -87,6 +91,12 @@
 #endif
 #endif
 
+#if _AIX && !defined(_ALL_SOURCE)
+#ifdef TIOCGWINSZ
+#undef TIOCGWINSZ
+#endif
+#endif
+
 void		erase P ((void));
 void		move P ((int row, int col));
 void		inverse P ((void));
diff --git a/MultiSource/Benchmarks/Prolangs-C/archie-client/support.c b/MultiSource/Benchmarks/Prolangs-C/archie-client/support.c
--- a/MultiSource/Benchmarks/Prolangs-C/archie-client/support.c
+++ b/MultiSource/Benchmarks/Prolangs-C/archie-client/support.c
@@ -4,6 +4,7 @@
  * For copying and distribution information, please see the file
  * <copyright.h>.
  *
+ * V1.2.3 - 06/18/20 (sw)  - add IBM AIX fix
  * v1.2.2 - 11/19/91 (mmt) - added MSDOS & OS2 stuff
  * v1.2.1 - 09/23/91 (gf)  - made it use regex.h---much nicer
  * v1.2.0 - 09/17/91 (bpk) - added BULL & USG stuff, thanks to Jim Sillas
@@ -42,6 +43,11 @@
 #  include <netdb.h>
 # endif
 # if !defined(MSDOS) || defined(OS2)
+// The header <sys/file.h> implicitly uses 'ushort', which is an
+// unknown type name to AIX when '_ALL_SOURCE' is not defined.
+#  if _AIX && !defined(_ALL_SOURCE)
+    typedef unsigned short ushort;
+#  endif
 #  include <sys/file.h>
 #  include <sys/param.h>
 # endif