diff --git a/plat/cpm/tests/build.lua b/plat/cpm/tests/build.lua
index 8795262ad..81d17d4dc 100644
--- a/plat/cpm/tests/build.lua
+++ b/plat/cpm/tests/build.lua
@@ -6,7 +6,8 @@ plat_testsuite {
     method = "plat/cpm/emu+emu",
     skipsets = {
         "b",      -- B is broken on i80
-        "floats"  -- floats aren't supported
+        "floats", -- floats aren't supported
+        "long-long",
     },
     tests = { "./*.c" },
 }
diff --git a/plat/linux68k/tests/build.lua b/plat/linux68k/tests/build.lua
index 6a4b847c8..221abc8d6 100644
--- a/plat/linux68k/tests/build.lua
+++ b/plat/linux68k/tests/build.lua
@@ -4,5 +4,8 @@ plat_testsuite {
     name = "tests",
     plat = "linux68k",
     method = "plat/linux68k/emu+emu68k",
-	skipsets = {"floats"}, -- FPU instructions not supported by emulator
+    skipsets = {
+        "floats", -- FPU instructions not supported by emulator
+        "long-long",
+    },
 }
diff --git a/plat/linuxmips/tests/build.lua b/plat/linuxmips/tests/build.lua
index 529277fd9..b2b660568 100644
--- a/plat/linuxmips/tests/build.lua
+++ b/plat/linuxmips/tests/build.lua
@@ -4,5 +4,7 @@ plat_testsuite {
     name = "tests",
     plat = "linuxmips",
     method = "qemu-mipsel",
---	skipsets = {"m2"},
+    skipsets = {
+        "long-long",
+    },
 }
diff --git a/plat/linuxppc/tests/build.lua b/plat/linuxppc/tests/build.lua
index 7ea6e5bb9..fe89558a6 100644
--- a/plat/linuxppc/tests/build.lua
+++ b/plat/linuxppc/tests/build.lua
@@ -3,5 +3,8 @@ include("tests/plat/build.lua")
 plat_testsuite {
     name = "tests",
     plat = "linuxppc",
-    method = "plat/linuxppc/emu+emuppc"
+    method = "plat/linuxppc/emu+emuppc",
+    skipsets = {
+        "long-long",
+    },
 }
diff --git a/plat/pc86/tests/build.lua b/plat/pc86/tests/build.lua
index 84b70a171..e4d8286fe 100644
--- a/plat/pc86/tests/build.lua
+++ b/plat/pc86/tests/build.lua
@@ -4,5 +4,8 @@ plat_testsuite {
     name = "tests",
     plat = "pc86",
     method = "plat/pc86/emu+pc86emu",
-	skipsets = {"floats"}, -- FPU instructions not supported by emulator
+    skipsets = {
+        "floats", -- FPU instructions not supported by emulator
+        "long-long",
+    },
 }
diff --git a/tests/plat/build.lua b/tests/plat/build.lua
index f7eecc0dd..72fd6afad 100644
--- a/tests/plat/build.lua
+++ b/tests/plat/build.lua
@@ -4,7 +4,7 @@ definerule("plat_testsuite",
 	{
 		plat = { type="string" },
 		method = { type="string" },
-		sets = { type="table", default={"core", "b", "bugs", "m2", "floats"}},
+		sets = { type="table", default={"core", "b", "bugs", "m2", "floats", "long-long"}},
 		skipsets = { type="table", default={}},
 		tests = { type="targets", default={} },
 	},
diff --git a/tests/plat/long-long/lladdsub_e.c b/tests/plat/long-long/lladdsub_e.c
new file mode 100644
index 000000000..a1b248520
--- /dev/null
+++ b/tests/plat/long-long/lladdsub_e.c
@@ -0,0 +1,59 @@
+#include "test.h"
+
+struct neg {
+	long long a;
+	long long neg_a; /* -a */
+} negations[] = {
+	{0LL, 0LL},
+	{2LL, -2LL},
+	{-446020022096LL, 446020022096LL},
+};
+
+struct s_addsub {
+	long long a;
+	long long b;
+	long long a_add_b; /* a + b */
+	long long a_sub_b; /* a - b */
+} s_cases[] = {
+	{2LL, 1LL, 3LL, 1LL},
+	{2LL, -1LL, 1LL, 3LL},
+	/* a + b overflows 32 bits */
+	{1930610480LL, 842500503LL, 2773110983LL, 1088109977LL},
+	{-446020022096LL, 1037107331549LL, 591087309453LL, -1483127353645LL},
+	{-737537585551LL, -847060446507LL, -1584598032058LL, 109522860956LL},
+};
+
+struct u_addsub {
+	unsigned long long a;
+	unsigned long long b;
+	unsigned long long a_add_b;
+	unsigned long long a_sub_b;
+} u_cases[] = {
+	{2ULL, 1ULL, 3ULL, 1ULL},
+	/* a + b overflows 63 bits */
+	{6092994517831567942ULL, 3716888886436146324ULL,
+	 9809883404267714266ULL, 2376105631395421618ULL},
+};
+
+#define LEN(ary) (sizeof(ary) / sizeof(ary[0]))
+
+void _m_a_i_n(void) {
+	int i;
+
+	for (i = 0; i < LEN(negations); i++) {
+		struct neg *n = &negations[i];
+		ASSERT(n->a == -n->neg_a);
+		ASSERT(-n->a == n->neg_a);
+	}
+	for (i = 0; i < LEN(s_cases); i++) {
+		struct s_addsub *s = &s_cases[i];
+		ASSERT(s->a + s->b == s->a_add_b);
+		ASSERT(s->a - s->b == s->a_sub_b);
+	}
+	for (i = 0; i < LEN(u_cases); i++) {
+		struct u_addsub *u = &u_cases[i];
+		ASSERT(u->a + u->b == u->a_add_b);
+		ASSERT(u->a - u->b == u->a_sub_b);
+	}
+	finished();
+}