diff --git a/Ghidra/Processors/ARM/certification.manifest b/Ghidra/Processors/ARM/certification.manifest
index 777e1f93dd..fc28f71729 100644
--- a/Ghidra/Processors/ARM/certification.manifest
+++ b/Ghidra/Processors/ARM/certification.manifest
@@ -26,6 +26,7 @@ data/languages/ARM8m_le.slaspec||GHIDRA||||END|
 data/languages/ARMCortex.pspec||GHIDRA||||END|
 data/languages/ARMTHUMBinstructions.sinc||GHIDRA||||END|
 data/languages/ARM_CDE.sinc||GHIDRA||||END|
+data/languages/ARM_apcs.cspec||GHIDRA||||END|
 data/languages/ARM_v45.cspec||GHIDRA||||END|
 data/languages/ARM_v45.pspec||GHIDRA||||END|
 data/languages/ARM_win.cspec||GHIDRA||||END|
diff --git a/Ghidra/Processors/ARM/data/languages/ARM.ldefs b/Ghidra/Processors/ARM/data/languages/ARM.ldefs
index 695e6bd3e7..e914419a8d 100644
--- a/Ghidra/Processors/ARM/data/languages/ARM.ldefs
+++ b/Ghidra/Processors/ARM/data/languages/ARM.ldefs
@@ -13,6 +13,7 @@
     <description>Generic ARM/Thumb v8 little endian</description>
     <compiler name="default" spec="ARM.cspec" id="default"/>
     <compiler name="Visual Studio" spec="ARM_win.cspec" id="windows"/>
+    <compiler name="APCS" spec="ARM_apcs.cspec" id="apcs"/>
     <external_name tool="gnu" name="iwmmxt"/>
     <external_name tool="gnu" name="armv8-a"/>
     <external_name tool="gnu" name="armv8-r"/>
@@ -36,6 +37,7 @@
     <description>Generic ARM/Thumb v8 little endian (Thumb is default)</description>
     <compiler name="default" spec="ARM.cspec" id="default"/>
     <compiler name="Visual Studio" spec="ARM_win.cspec" id="windows"/>
+    <compiler name="APCS" spec="ARM_apcs.cspec" id="apcs"/>    
     <external_name tool="gnu" name="iwmmxt"/>
     <external_name tool="gnu" name="arm_any"/>
     <external_name tool="gdis.disassembler.options.file" name="ARM.gdis"/>
@@ -58,6 +60,7 @@
     <description>Generic ARM/Thumb v8 little endian instructions and big endian data</description>
     <compiler name="default" spec="ARM.cspec" id="default"/>
     <compiler name="Visual Studio" spec="ARM.cspec" id="windows"/>
+    <compiler name="APCS" spec="ARM_apcs.cspec" id="apcs"/>
     <external_name tool="DWARF.register.mapping.file" name="ARMneon.dwarf"/>
   </language>
   
@@ -72,6 +75,7 @@
             id="ARM:BE:32:v8">
     <description>Generic ARM/Thumb v8 big endian</description>
     <compiler name="default" spec="ARM.cspec" id="default"/>
+    <compiler name="APCS" spec="ARM_apcs.cspec" id="apcs"/>
     <external_name tool="gnu" name="iwmmxt"/>
     <external_name tool="gnu" name="armv8-a"/>
     <external_name tool="gnu" name="armv8-r"/>
@@ -94,6 +98,7 @@
             id="ARM:BE:32:v8T">
     <description>Generic ARM/Thumb v8 big endian (Thumb is default)</description>
     <compiler name="default" spec="ARM.cspec" id="default"/>
+    <compiler name="APCS" spec="ARM_apcs.cspec" id="apcs"/>
     <external_name tool="gnu" name="iwmmxt"/>
     <external_name tool="gnu" name="arm_any"/>
     <external_name tool="IDA-PRO" name="armb"/>
@@ -114,6 +119,7 @@
     <description>Generic ARM/Thumb v7 little endian</description>
     <compiler name="default" spec="ARM.cspec" id="default"/>
     <compiler name="Visual Studio" spec="ARM_win.cspec" id="windows"/>
+    <compiler name="APCS" spec="ARM_apcs.cspec" id="apcs"/>
     <external_name tool="gnu" name="iwmmxt"/>
     <external_name tool="gnu" name="armv7"/>
     <external_name tool="gdis.disassembler.options.file" name="ARM.gdis"/>
@@ -136,6 +142,7 @@
     <description>Generic ARM/Thumb v7 little endian instructions and big endian data</description>
     <compiler name="default" spec="ARM.cspec" id="default"/>
     <compiler name="Visual Studio" spec="ARM.cspec" id="windows"/>
+    <compiler name="APCS" spec="ARM_apcs.cspec" id="apcs"/>
     <external_name tool="DWARF.register.mapping.file" name="ARMneon.dwarf"/>
   </language>
   
@@ -150,6 +157,7 @@
             id="ARM:BE:32:v7">
     <description>Generic ARM/Thumb v7 big endian</description>
     <compiler name="default" spec="ARM.cspec" id="default"/>
+    <compiler name="APCS" spec="ARM_apcs.cspec" id="apcs"/>
     <external_name tool="gnu" name="iwmmxt"/>
     <external_name tool="gnu" name="armv7"/>
     <external_name tool="gdis.disassembler.options.file" name="ARM.gdis"/>
@@ -170,6 +178,7 @@
             id="ARM:LE:32:Cortex">
     <description>ARM Cortex / Thumb little endian</description>
     <compiler name="default" spec="ARM.cspec" id="default"/>
+    <compiler name="APCS" spec="ARM_apcs.cspec" id="apcs"/>
     <external_name tool="gnu" name="armv7e-m"/>
     <external_name tool="gnu" name="armv6k"/>
     <external_name tool="gnu" name="armv6kz"/>
@@ -193,6 +202,7 @@
             id="ARM:BE:32:Cortex">
     <description>ARM Cortex / Thumb big endian</description>
     <compiler name="default" spec="ARM.cspec" id="default"/>
+    <compiler name="APCS" spec="ARM_apcs.cspec" id="apcs"/>
     <external_name tool="gnu" name="armv6k"/>
     <external_name tool="gnu" name="armv6kz"/>
     <external_name tool="gnu" name="armv6-m"/>
@@ -215,6 +225,7 @@
             id="ARM:LE:32:v8-m">
     <description>ARM Cortex v8-m little endian</description>
     <compiler name="default" spec="ARM.cspec" id="default"/>
+    <compiler name="APCS" spec="ARM_apcs.cspec" id="apcs"/>
     <external_name tool="gnu" name="armv8-m.base"/>
     <external_name tool="gnu" name="armv8-m.main"/>
     <external_name tool="gnu" name="armv8.1-m.main"/>
@@ -232,6 +243,7 @@
             id="ARM:BE:32:v8-m">
     <description>ARM Cortex v8-m big endian</description>
     <compiler name="default" spec="ARM.cspec" id="default"/>
+    <compiler name="APCS" spec="ARM_apcs.cspec" id="apcs"/>
     <external_name tool="gnu" name="armv8-m.base"/>
     <external_name tool="gnu" name="armv8-m.main"/>
     <external_name tool="gnu" name="armv8.1-m.main"/>
@@ -250,6 +262,7 @@
             id="ARM:LE:32:v6">
     <description>Generic ARM/Thumb v6 little endian</description>
     <compiler name="default" spec="ARM_v45.cspec" id="default"/>
+    <compiler name="APCS" spec="ARM_apcs.cspec" id="apcs"/>
     <external_name tool="gnu" name="xscale"/>
     <external_name tool="gnu" name="armv6"/>
     <external_name tool="gdis.disassembler.options.file" name="ARM.gdis"/>
@@ -272,6 +285,7 @@
             id="ARM:BE:32:v6">
     <description>Generic ARM/Thumb v6 big endian</description>
     <compiler name="default" spec="ARM_v45.cspec" id="default"/>
+    <compiler name="APCS" spec="ARM_apcs.cspec" id="apcs"/>
     <external_name tool="gnu" name="xscale"/>
     <external_name tool="gnu" name="armv6"/>
     <external_name tool="gdis.disassembler.options.file" name="ARM.gdis"/>
@@ -294,6 +308,7 @@
             id="ARM:LE:32:v5t">
     <description>Generic ARM/Thumb v5 little endian (T-variant)</description>
     <compiler name="default" spec="ARM_v45.cspec" id="default"/>
+    <compiler name="APCS" spec="ARM_apcs.cspec" id="apcs"/>
     <external_name tool="gnu" name="armv5t"/>
     <external_name tool="gnu" name="armv5tej"/>
     <external_name tool="gdis.disassembler.options.file" name="ARM.gdis"/>
@@ -314,6 +329,7 @@
             id="ARM:BE:32:v5t">
     <description>Generic ARM/Thumb v5 big endian (T-variant)</description>
     <compiler name="default" spec="ARM_v45.cspec" id="default"/>
+    <compiler name="APCS" spec="ARM_apcs.cspec" id="apcs"/>
     <external_name tool="gnu" name="armv5t"/>
     <external_name tool="gnu" name="armv5tej"/>
     <external_name tool="gdis.disassembler.options.file" name="ARM.gdis"/>
@@ -334,6 +350,7 @@
             id="ARM:LE:32:v5">
     <description>Generic ARM v5 little endian</description>
     <compiler name="default" spec="ARM_v45.cspec" id="default"/>
+    <compiler name="APCS" spec="ARM_apcs.cspec" id="apcs"/>
     <external_name tool="gnu" name="armv5"/>
     <external_name tool="IDA-PRO" name="arm"/>
     <external_name tool="DWARF.register.mapping.file" name="ARM.dwarf"/>
@@ -352,6 +369,7 @@
             id="ARM:BE:32:v5">
     <description>Generic ARM v5 big endian</description>
     <compiler name="default" spec="ARM_v45.cspec" id="default"/>
+    <compiler name="APCS" spec="ARM_apcs.cspec" id="apcs"/>
     <external_name tool="gnu" name="armv5"/>
     <external_name tool="IDA-PRO" name="armb"/>
     <external_name tool="DWARF.register.mapping.file" name="ARM.dwarf"/>
@@ -370,6 +388,7 @@
             id="ARM:LE:32:v4t"> 
     <description>Generic ARM/Thumb v4 little endian (T-variant)</description>
     <compiler name="default" spec="ARM_v45.cspec" id="default"/>
+    <compiler name="APCS" spec="ARM_apcs.cspec" id="apcs"/>
     <external_name tool="gnu" name="armv4t"/>
     <external_name tool="gdis.disassembler.options.file" name="ARM.gdis"/>
     <external_name tool="IDA-PRO" name="arm"/>
@@ -389,6 +408,7 @@
             id="ARM:BE:32:v4t">
     <description>Generic ARM/Thumb v4 big endian (T-variant)</description>
     <compiler name="default" spec="ARM_v45.cspec" id="default"/>
+    <compiler name="APCS" spec="ARM_apcs.cspec" id="apcs"/>
     <external_name tool="gnu" name="armv4t"/>
     <external_name tool="gdis.disassembler.options.file" name="ARM.gdis"/>
     <external_name tool="IDA-PRO" name="armb"/>
@@ -408,6 +428,7 @@
             id="ARM:LE:32:v4">
     <description>Generic ARM v4 little endian</description>
     <compiler name="default" spec="ARM_v45.cspec" id="default"/>
+    <compiler name="APCS" spec="ARM_apcs.cspec" id="apcs"/>
     <external_name tool="gnu" name="armv4"/>
     <external_name tool="gnu" name="armv2"/>
     <external_name tool="gnu" name="armv2a"/>
@@ -430,6 +451,7 @@
             id="ARM:BE:32:v4">
     <description>Generic ARM v4 big endian</description>
     <compiler name="default" spec="ARM_v45.cspec" id="default"/>
+    <compiler name="APCS" spec="ARM_apcs.cspec" id="apcs"/>
     <external_name tool="gnu" name="armv4"/>
     <external_name tool="gnu" name="armv2"/>
     <external_name tool="gnu" name="armv2a"/>
diff --git a/Ghidra/Processors/ARM/data/languages/ARM_apcs.cspec b/Ghidra/Processors/ARM/data/languages/ARM_apcs.cspec
new file mode 100644
index 0000000000..406734fa88
--- /dev/null
+++ b/Ghidra/Processors/ARM/data/languages/ARM_apcs.cspec
@@ -0,0 +1,299 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<compiler_spec>
+  <!--
+  	Assumes compilation with the deprecated ARM APCS standard. In gcc, compilation with
+  	-mabi=apcs-gnu or -mabi=atpcs
+  -->
+  <data_organization>  <!-- These tags were generated with gcc 4.2.4 -->
+     <absolute_max_alignment value="0" />
+     <machine_alignment value="2" />
+     <default_alignment value="1" />
+     <default_pointer_alignment value="4" />
+     <pointer_size value="4" />
+     <wchar_size value="4" />
+     <short_size value="2" />
+     <integer_size value="4" />
+     <long_size value="4" />
+     <long_long_size value="8" />
+     <float_size value="4" />
+     <double_size value="8" />
+     <long_double_size value="8" />
+     <size_alignment_map>
+          <entry size="1" alignment="1" />
+          <entry size="2" alignment="2" />
+          <entry size="4" alignment="4" />
+          <entry size="8" alignment="4" />
+     </size_alignment_map>
+  </data_organization>
+  <global>
+    <range space="ram"/>
+  </global>
+  <stackpointer register="sp" space="ram"/>
+  
+  <funcptr align="2"/>     <!-- Function pointers are word aligned and leastsig bit may encode otherstuff -->
+  <default_proto>
+    <prototype name="__stdcall" extrapop="0" stackshift="0"> <!-- Compilation with -mabi=atpcs -->
+    <!-- Return structs and unions that fit into a single register in registers. 
+         Any larger structs and unions are returned by pointer. -->
+      <input>
+        <pentry minsize="1" maxsize="4" extension="inttype">
+          <register name="r0"/>
+        </pentry>
+        <pentry minsize="1" maxsize="4" extension="inttype">
+          <register name="r1"/>
+        </pentry>
+        <pentry minsize="1" maxsize="4" extension="inttype">
+          <register name="r2"/>
+        </pentry>
+        <pentry minsize="1" maxsize="4" extension="inttype">
+          <register name="r3"/>
+        </pentry>
+        <pentry minsize="1" maxsize="500" align="4">
+          <addr offset="0" space="stack"/>
+        </pentry>
+        <rule>
+          <datatype name="any"/>
+          <join/>
+        </rule>
+      </input>
+      <output>
+        <pentry minsize="1" maxsize="4" extension="inttype">
+          <register name="r0"/>
+        </pentry>
+        <pentry minsize="1" maxsize="4" extension="inttype">
+          <register name="r1"/>
+        </pentry>
+        <rule>
+          <datatype name="struct" minsize="5"/>
+          <hidden_return/>
+        </rule>
+        <rule>
+          <datatype name="union" minsize="5"/>
+          <hidden_return/>
+        </rule>
+        <rule>
+          <datatype name="any"/>
+          <join/>
+        </rule>
+      </output>
+      <unaffected>
+        <register name="r4"/>
+        <register name="r5"/>
+        <register name="r6"/>
+        <register name="r7"/>
+        <register name="r8"/>
+        <register name="r9"/>
+        <register name="r10"/>
+        <register name="r11"/>
+        <register name="sp"/>
+      </unaffected>
+      <killedbycall>
+          <register name="r0"/>
+          <register name="r1"/>
+          <register name="r2"/>
+          <register name="r3"/>
+          <register name="r12"/>
+      </killedbycall>
+    </prototype>
+  </default_proto>
+  <prototype name="__gnu_stdcall" extrapop="0" stackshift="0"> <!-- Compilation with -mabi=apcs-gnu -->
+  <!-- Return all structs and unions by pointer -->
+    <input>
+      <pentry minsize="1" maxsize="4" extension="inttype">
+        <register name="r0"/>
+      </pentry>
+      <pentry minsize="1" maxsize="4" extension="inttype">
+        <register name="r1"/>
+      </pentry>
+      <pentry minsize="1" maxsize="4" extension="inttype">
+        <register name="r2"/>
+      </pentry>
+      <pentry minsize="1" maxsize="4" extension="inttype">
+        <register name="r3"/>
+      </pentry>
+      <pentry minsize="1" maxsize="500" align="4">
+        <addr offset="0" space="stack"/>
+      </pentry>
+      <rule>
+        <datatype name="any"/>
+        <join/>
+      </rule>
+    </input>
+    <output>
+      <pentry minsize="1" maxsize="4" extension="inttype">
+        <register name="r0"/>
+      </pentry>
+      <pentry minsize="1" maxsize="4" extension="inttype">
+        <register name="r1"/>
+      </pentry>
+      <rule>
+        <datatype name="struct"/>
+        <hidden_return/>
+      </rule>
+      <rule>
+        <datatype name="union"/>
+        <hidden_return/>
+      </rule>
+      <rule>
+        <datatype name="any"/>
+        <join/>
+      </rule>
+    </output>
+    <unaffected>
+      <register name="r4"/>
+      <register name="r5"/>
+      <register name="r6"/>
+      <register name="r7"/>
+      <register name="r8"/>
+      <register name="r9"/>
+      <register name="r10"/>
+      <register name="r11"/>
+      <register name="sp"/>
+    </unaffected>
+    <killedbycall>
+      <register name="r0"/>
+      <register name="r1"/>
+      <register name="r2"/>
+      <register name="r3"/>
+      <register name="r12"/>
+    </killedbycall>
+  </prototype>
+  
+  <callotherfixup targetop="setISAMode">
+    <pcode incidentalcopy="true">
+      <!-- NOP -->
+      <body><![CDATA[
+        r0 = r0;
+      ]]></body>
+    </pcode>
+  </callotherfixup>
+  
+  <callfixup name="switch8_r3">
+    <target name="switch8_r3"/>
+    <target name="__ARM_common_switch8"/>
+    <pcode>
+      <body><![CDATA[
+            tmpptr = lr - 1;
+            tblsize = *:1 tmpptr;
+            r12 = zext(tblsize);
+
+            inbounds = r3 < r12;
+            
+            if (!inbounds) goto <next1>;
+            offset = *:1 (lr + r3);
+            r3 = zext(offset);
+            <next1>
+            
+            if (inbounds) goto <next2>;
+            offset = *:1 (lr + r12);
+            r3 = zext(offset);
+            <next2>
+            
+            r3 = r3 * 2;
+            
+            r12 = lr + r3;
+            
+            ISAModeSwitch = (r12 & 1) != 1;
+            TB = ISAModeSwitch;
+            pc = r12 & 0xfffffffe;
+            goto [pc];
+      ]]></body>
+    </pcode>
+  </callfixup>
+  
+  <callfixup name="switch8_r0">
+    <target name="__gnu_thumb1_case_uqi"/>
+    <target name="switch8_r0"/>
+    <pcode>
+      <body><![CDATA[
+            tmpptr = lr & 0xfffffffe;
+
+            offset = *:1 (tmpptr + r0);
+            lr = lr + 2 * zext(offset);
+ 
+            ISAModeSwitch = (lr & 1) != 0;
+            TB = ISAModeSwitch;
+            pc = lr & 0xfffffffe;
+            goto [pc];
+      ]]></body>
+    </pcode>
+  </callfixup>
+  
+  <callfixup name="switchS8_r0">
+    <target name="__gnu_thumb1_case_sqi"/>
+    <target name="switchS8_r0"/>
+    <pcode>
+      <body><![CDATA[
+            tmpptr = lr & 0xfffffffe;
+
+            offset = *:1 (tmpptr + r0);
+            lr = lr + 2 * sext(offset);
+ 
+            ISAModeSwitch = (lr & 1) != 0;
+            TB = ISAModeSwitch;
+            pc = lr & 0xfffffffe;
+            goto [pc];
+      ]]></body>
+    </pcode>
+  </callfixup>
+  
+  <callfixup name="switch16_shi_r0">
+    <target name="__gnu_thumb1_case_shi"/>
+    <target name="switch16_shi_r0"/>
+    <pcode>
+      <body><![CDATA[
+            tmpptr = lr & 0xfffffffe;
+            
+            index = r0 * 2;
+            offset = *:2 (tmpptr + index);
+            lr = lr + 2 * sext(offset);
+ 
+            ISAModeSwitch = (lr & 1) != 0;
+            TB = ISAModeSwitch;
+            pc = lr & 0xfffffffe;
+            goto [pc];
+      ]]></body>
+    </pcode>
+  </callfixup>
+  
+  <callfixup name="switch16_uhi_r0">
+    <target name="__gnu_thumb1_case_uhi"/>
+    <target name="switch16_shi_r0"/>
+    <pcode>
+      <body><![CDATA[
+            tmpptr = lr & 0xfffffffe;
+            
+            index = r0 * 2;
+            offset = *:2 (tmpptr + index);
+            lr = lr + 2 * zext(offset);
+ 
+            ISAModeSwitch = (lr & 1) != 0;
+            TB = ISAModeSwitch;
+            pc = lr & 0xfffffffe;
+            goto [pc];
+      ]]></body>
+    </pcode>
+  </callfixup>
+  
+  <callfixup name="switch32_si_r0">
+    <target name="__gnu_thumb1_case_si"/>
+    <target name="switch32_si_r0"/>
+    <pcode>
+      <body><![CDATA[
+            tmpptr = (lr + 2) & 0xfffffffc;
+            
+            index = r0 * 4;
+            offset = *:4 (tmpptr + index);
+            offset = offset * 4;
+            lr = lr + offset;
+ 
+            ISAModeSwitch = (lr & 1) != 0;
+            TB = ISAModeSwitch;
+            pc = lr & 0xfffffffe;
+            goto [pc];
+      ]]></body>
+    </pcode>
+  </callfixup>
+  
+</compiler_spec>