diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8599d01a5..94219c163 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -288,6 +288,7 @@ set(ZIG_SOURCES
     "${CMAKE_SOURCE_DIR}/src/target.cpp"
     "${CMAKE_SOURCE_DIR}/src/tokenizer.cpp"
     "${CMAKE_SOURCE_DIR}/src/util.cpp"
+    "${CMAKE_SOURCE_DIR}/src/softfloat_ext.cpp"
     "${ZIG_SOURCES_MEM_PROFILE}"
 )
 set(OPTIMIZED_C_SOURCES
diff --git a/lib/std/math.zig b/lib/std/math.zig
index 5cf6d40d8..799c42846 100644
--- a/lib/std/math.zig
+++ b/lib/std/math.zig
@@ -122,6 +122,11 @@ pub fn forceEval(value: var) void {
             const p = @ptrCast(*volatile f64, &x);
             p.* = x;
         },
+        f128 => {
+            var x: f128 = undefined;
+            const p = @ptrCast(*volatile f128, &x);
+            p.* = x;
+        },
         else => {
             @compileError("forceEval not implemented for " ++ @typeName(T));
         },
diff --git a/lib/std/math/ceil.zig b/lib/std/math/ceil.zig
index b94e13a17..e3b567931 100644
--- a/lib/std/math/ceil.zig
+++ b/lib/std/math/ceil.zig
@@ -20,6 +20,7 @@ pub fn ceil(x: var) @TypeOf(x) {
     return switch (T) {
         f32 => ceil32(x),
         f64 => ceil64(x),
+        f128 => ceil128(x),
         else => @compileError("ceil not implemented for " ++ @typeName(T)),
     };
 }
@@ -86,9 +87,37 @@ fn ceil64(x: f64) f64 {
     }
 }
 
+fn ceil128(x: f128) f128 {
+    const u = @bitCast(u128, x);
+    const e = (u >> 112) & 0x7FFF;
+    var y: f128 = undefined;
+
+    if (e >= 0x3FFF + 112 or x == 0) return x;
+
+    if (u >> 127 != 0) {
+        y = x - math.f128_toint + math.f128_toint - x;
+    } else {
+        y = x + math.f128_toint - math.f128_toint - x;
+    }
+
+    if (e <= 0x3FFF - 1) {
+        math.forceEval(y);
+        if (u >> 127 != 0) {
+            return -0.0;
+        } else {
+            return 1.0;
+        }
+    } else if (y < 0) {
+        return x + y + 1;
+    } else {
+        return x + y;
+    }
+}
+
 test "math.ceil" {
     expect(ceil(@as(f32, 0.0)) == ceil32(0.0));
     expect(ceil(@as(f64, 0.0)) == ceil64(0.0));
+    expect(ceil(@as(f128, 0.0)) == ceil128(0.0));
 }
 
 test "math.ceil32" {
@@ -103,6 +132,12 @@ test "math.ceil64" {
     expect(ceil64(0.2) == 1.0);
 }
 
+test "math.ceil128" {
+    expect(ceil128(1.3) == 2.0);
+    expect(ceil128(-1.3) == -1.0);
+    expect(ceil128(0.2) == 1.0);
+}
+
 test "math.ceil32.special" {
     expect(ceil32(0.0) == 0.0);
     expect(ceil32(-0.0) == -0.0);
@@ -118,3 +153,11 @@ test "math.ceil64.special" {
     expect(math.isNegativeInf(ceil64(-math.inf(f64))));
     expect(math.isNan(ceil64(math.nan(f64))));
 }
+
+test "math.ceil128.special" {
+    expect(ceil128(0.0) == 0.0);
+    expect(ceil128(-0.0) == -0.0);
+    expect(math.isPositiveInf(ceil128(math.inf(f128))));
+    expect(math.isNegativeInf(ceil128(-math.inf(f128))));
+    expect(math.isNan(ceil128(math.nan(f128))));
+}
diff --git a/lib/std/math/floor.zig b/lib/std/math/floor.zig
index 1eda362e6..565e2911a 100644
--- a/lib/std/math/floor.zig
+++ b/lib/std/math/floor.zig
@@ -21,6 +21,7 @@ pub fn floor(x: var) @TypeOf(x) {
         f16 => floor16(x),
         f32 => floor32(x),
         f64 => floor64(x),
+        f128 => floor128(x),
         else => @compileError("floor not implemented for " ++ @typeName(T)),
     };
 }
@@ -122,10 +123,38 @@ fn floor64(x: f64) f64 {
     }
 }
 
+fn floor128(x: f128) f128 {
+    const u = @bitCast(u128, x);
+    const e = (u >> 112) & 0x7FFF;
+    var y: f128 = undefined;
+
+    if (e >= 0x3FFF + 112 or x == 0) return x;
+
+    if (u >> 127 != 0) {
+        y = x - math.f128_toint + math.f128_toint - x;
+    } else {
+        y = x + math.f128_toint - math.f128_toint - x;
+    }
+
+    if (e <= 0x3FFF - 1) {
+        math.forceEval(y);
+        if (u >> 127 != 0) {
+            return -1.0;
+        } else {
+            return 0.0;
+        }
+    } else if (y > 0) {
+        return x + y - 1;
+    } else {
+        return x + y;
+    }
+}
+
 test "math.floor" {
     expect(floor(@as(f16, 1.3)) == floor16(1.3));
     expect(floor(@as(f32, 1.3)) == floor32(1.3));
     expect(floor(@as(f64, 1.3)) == floor64(1.3));
+    expect(floor(@as(f128, 1.3)) == floor128(1.3));
 }
 
 test "math.floor16" {
@@ -146,6 +175,12 @@ test "math.floor64" {
     expect(floor64(0.2) == 0.0);
 }
 
+test "math.floor128" {
+    expect(floor128(1.3) == 1.0);
+    expect(floor128(-1.3) == -2.0);
+    expect(floor128(0.2) == 0.0);
+}
+
 test "math.floor16.special" {
     expect(floor16(0.0) == 0.0);
     expect(floor16(-0.0) == -0.0);
@@ -169,3 +204,11 @@ test "math.floor64.special" {
     expect(math.isNegativeInf(floor64(-math.inf(f64))));
     expect(math.isNan(floor64(math.nan(f64))));
 }
+
+test "math.floor128.special" {
+    expect(floor128(0.0) == 0.0);
+    expect(floor128(-0.0) == -0.0);
+    expect(math.isPositiveInf(floor128(math.inf(f128))));
+    expect(math.isNegativeInf(floor128(-math.inf(f128))));
+    expect(math.isNan(floor128(math.nan(f128))));
+}
diff --git a/lib/std/math/round.zig b/lib/std/math/round.zig
index dceb3ed77..052c0f767 100644
--- a/lib/std/math/round.zig
+++ b/lib/std/math/round.zig
@@ -20,6 +20,7 @@ pub fn round(x: var) @TypeOf(x) {
     return switch (T) {
         f32 => round32(x),
         f64 => round64(x),
+        f128 => round128(x),
         else => @compileError("round not implemented for " ++ @typeName(T)),
     };
 }
@@ -90,9 +91,43 @@ fn round64(x_: f64) f64 {
     }
 }
 
+fn round128(x_: f128) f128 {
+    var x = x_;
+    const u = @bitCast(u128, x);
+    const e = (u >> 112) & 0x7FFF;
+    var y: f128 = undefined;
+
+    if (e >= 0x3FFF + 112) {
+        return x;
+    }
+    if (u >> 127 != 0) {
+        x = -x;
+    }
+    if (e < 0x3FFF - 1) {
+        math.forceEval(x + math.f64_toint);
+        return 0 * @bitCast(f128, u);
+    }
+
+    y = x + math.f128_toint - math.f128_toint - x;
+    if (y > 0.5) {
+        y = y + x - 1;
+    } else if (y <= -0.5) {
+        y = y + x + 1;
+    } else {
+        y = y + x;
+    }
+
+    if (u >> 127 != 0) {
+        return -y;
+    } else {
+        return y;
+    }
+}
+
 test "math.round" {
     expect(round(@as(f32, 1.3)) == round32(1.3));
     expect(round(@as(f64, 1.3)) == round64(1.3));
+    expect(round(@as(f128, 1.3)) == round128(1.3));
 }
 
 test "math.round32" {
@@ -109,6 +144,13 @@ test "math.round64" {
     expect(round64(1.8) == 2.0);
 }
 
+test "math.round128" {
+    expect(round128(1.3) == 1.0);
+    expect(round128(-1.3) == -1.0);
+    expect(round128(0.2) == 0.0);
+    expect(round128(1.8) == 2.0);
+}
+
 test "math.round32.special" {
     expect(round32(0.0) == 0.0);
     expect(round32(-0.0) == -0.0);
@@ -124,3 +166,11 @@ test "math.round64.special" {
     expect(math.isNegativeInf(round64(-math.inf(f64))));
     expect(math.isNan(round64(math.nan(f64))));
 }
+
+test "math.round128.special" {
+    expect(round128(0.0) == 0.0);
+    expect(round128(-0.0) == -0.0);
+    expect(math.isPositiveInf(round128(math.inf(f128))));
+    expect(math.isNegativeInf(round128(-math.inf(f128))));
+    expect(math.isNan(round128(math.nan(f128))));
+}
diff --git a/lib/std/math/trunc.zig b/lib/std/math/trunc.zig
index b70f0c6be..cdd2fa3c6 100644
--- a/lib/std/math/trunc.zig
+++ b/lib/std/math/trunc.zig
@@ -20,6 +20,7 @@ pub fn trunc(x: var) @TypeOf(x) {
     return switch (T) {
         f32 => trunc32(x),
         f64 => trunc64(x),
+        f128 => trunc128(x),
         else => @compileError("trunc not implemented for " ++ @typeName(T)),
     };
 }
@@ -66,9 +67,31 @@ fn trunc64(x: f64) f64 {
     }
 }
 
+fn trunc128(x: f128) f128 {
+    const u = @bitCast(u128, x);
+    var e = @intCast(i32, ((u >> 112) & 0x7FFF)) - 0x3FFF + 16;
+    var m: u128 = undefined;
+
+    if (e >= 112 + 16) {
+        return x;
+    }
+    if (e < 16) {
+        e = 1;
+    }
+
+    m = @as(u128, maxInt(u128)) >> @intCast(u7, e);
+    if (u & m == 0) {
+        return x;
+    } else {
+        math.forceEval(x + 0x1p120);
+        return @bitCast(f128, u & ~m);
+    }
+}
+
 test "math.trunc" {
     expect(trunc(@as(f32, 1.3)) == trunc32(1.3));
     expect(trunc(@as(f64, 1.3)) == trunc64(1.3));
+    expect(trunc(@as(f128, 1.3)) == trunc128(1.3));
 }
 
 test "math.trunc32" {
@@ -83,6 +106,12 @@ test "math.trunc64" {
     expect(trunc64(0.2) == 0.0);
 }
 
+test "math.trunc128" {
+    expect(trunc128(1.3) == 1.0);
+    expect(trunc128(-1.3) == -1.0);
+    expect(trunc128(0.2) == 0.0);
+}
+
 test "math.trunc32.special" {
     expect(trunc32(0.0) == 0.0); // 0x3F800000
     expect(trunc32(-0.0) == -0.0);
@@ -98,3 +127,11 @@ test "math.trunc64.special" {
     expect(math.isNegativeInf(trunc64(-math.inf(f64))));
     expect(math.isNan(trunc64(math.nan(f64))));
 }
+
+test "math.trunc128.special" {
+    expect(trunc128(0.0) == 0.0);
+    expect(trunc128(-0.0) == -0.0);
+    expect(math.isPositiveInf(trunc128(math.inf(f128))));
+    expect(math.isNegativeInf(trunc128(-math.inf(f128))));
+    expect(math.isNan(trunc128(math.nan(f128))));
+}
diff --git a/src/ir.cpp b/src/ir.cpp
index 48e5db8f2..273a015d0 100644
--- a/src/ir.cpp
+++ b/src/ir.cpp
@@ -13,6 +13,7 @@
 #include "os.hpp"
 #include "range_set.hpp"
 #include "softfloat.hpp"
+#include "softfloat_ext.hpp"
 #include "util.hpp"
 #include "mem_list.hpp"
 #include "all_types.hpp"
@@ -30278,6 +30279,21 @@ static ErrorMsg *ir_eval_float_op(IrAnalyze *ira, IrInst* source_instr, BuiltinF
         case BuiltinFnIdSqrt:
             f128M_sqrt(in, out);
             break;
+        case BuiltinFnIdFabs:
+            f128M_abs(in, out);
+            break;
+        case BuiltinFnIdFloor:
+            f128M_roundToInt(in, softfloat_round_min, false, out);
+            break;
+        case BuiltinFnIdCeil:
+            f128M_roundToInt(in, softfloat_round_max, false, out);
+        break;
+        case BuiltinFnIdTrunc:
+            f128M_trunc(in, out);
+            break;
+        case BuiltinFnIdRound: 
+            f128M_roundToInt(in, softfloat_round_near_maxMag, false, out);
+            break;
         case BuiltinFnIdNearbyInt:
         case BuiltinFnIdSin:
         case BuiltinFnIdCos:
@@ -30286,11 +30302,6 @@ static ErrorMsg *ir_eval_float_op(IrAnalyze *ira, IrInst* source_instr, BuiltinF
         case BuiltinFnIdLog:
         case BuiltinFnIdLog10:
         case BuiltinFnIdLog2:
-        case BuiltinFnIdFabs:
-        case BuiltinFnIdFloor:
-        case BuiltinFnIdCeil:
-        case BuiltinFnIdTrunc:
-        case BuiltinFnIdRound:
             return ir_add_error(ira, source_instr,
                 buf_sprintf("compiler bug: TODO: implement '%s' for type '%s'. See https://github.com/ziglang/zig/issues/4026",
                     float_op_to_name(fop), buf_ptr(&float_type->name)));
diff --git a/src/softfloat_ext.cpp b/src/softfloat_ext.cpp
new file mode 100644
index 000000000..8408a1511
--- /dev/null
+++ b/src/softfloat_ext.cpp
@@ -0,0 +1,25 @@
+#include "softfloat_ext.hpp"
+
+extern "C" {
+    #include "softfloat.h"
+}
+
+void f128M_abs(const float128_t *aPtr, float128_t *zPtr) {
+    float128_t zero_float;
+    ui32_to_f128M(0, &zero_float);
+    if (f128M_lt(aPtr, &zero_float)) {
+        f128M_sub(&zero_float, aPtr, zPtr);
+    } else {
+        *zPtr = *aPtr;
+    } 
+}
+
+void f128M_trunc(const float128_t *aPtr, float128_t *zPtr) {
+    float128_t zero_float;
+    ui32_to_f128M(0, &zero_float);
+    if (f128M_lt(aPtr, &zero_float)) {
+        f128M_roundToInt(aPtr, softfloat_round_max, false, zPtr);
+    } else {
+        f128M_roundToInt(aPtr, softfloat_round_min, false, zPtr);
+    } 
+}
\ No newline at end of file
diff --git a/src/softfloat_ext.hpp b/src/softfloat_ext.hpp
new file mode 100644
index 000000000..0a1f95893
--- /dev/null
+++ b/src/softfloat_ext.hpp
@@ -0,0 +1,9 @@
+#ifndef ZIG_SOFTFLOAT_EXT_HPP
+#define ZIG_SOFTFLOAT_EXT_HPP
+
+#include "softfloat_types.h"
+
+void f128M_abs(const float128_t *aPtr, float128_t *zPtr);
+void f128M_trunc(const float128_t *aPtr, float128_t *zPtr);
+
+#endif
\ No newline at end of file
diff --git a/test/stage1/behavior/math.zig b/test/stage1/behavior/math.zig
index 1d361494e..b13b1ce1e 100644
--- a/test/stage1/behavior/math.zig
+++ b/test/stage1/behavior/math.zig
@@ -634,6 +634,128 @@ fn testSqrt(comptime T: type, x: T) void {
     expect(@sqrt(x * x) == x);
 }
 
+test "@fabs" {
+    testFabs(f128, 12.0);
+    comptime testFabs(f128, 12.0);
+    testFabs(f64, 12.0);
+    comptime testFabs(f64, 12.0);
+    testFabs(f32, 12.0);
+    comptime testFabs(f32, 12.0);
+    testFabs(f16, 12.0);
+    comptime testFabs(f16, 12.0);
+
+    const x = 14.0;
+    const y = -x;
+    const z = @fabs(y);
+    comptime expectEqual(x, z);
+}
+
+fn testFabs(comptime T: type, x: T) void {
+    const y = -x;
+    const z = @fabs(y);
+    expectEqual(x, z);
+}
+
+test "@floor" {
+    // FIXME: Generates a floorl function call
+    // testFloor(f128, 12.0);
+    comptime testFloor(f128, 12.0);
+    testFloor(f64, 12.0);
+    comptime testFloor(f64, 12.0);
+    testFloor(f32, 12.0);
+    comptime testFloor(f32, 12.0);
+    testFloor(f16, 12.0);
+    comptime testFloor(f16, 12.0);
+
+    const x = 14.0;
+    const y = x + 0.7;
+    const z = @floor(y);
+    comptime expectEqual(x, z);
+}
+
+fn testFloor(comptime T: type, x: T) void {
+    const y = x + 0.6;
+    const z = @floor(y);
+    expectEqual(x, z);
+}
+
+test "@ceil" {
+    // FIXME: Generates a ceill function call
+    //testCeil(f128, 12.0);
+    comptime testCeil(f128, 12.0);
+    testCeil(f64, 12.0);
+    comptime testCeil(f64, 12.0);
+    testCeil(f32, 12.0);
+    comptime testCeil(f32, 12.0);
+    testCeil(f16, 12.0);
+    comptime testCeil(f16, 12.0);
+
+    const x = 14.0;
+    const y = x - 0.7;
+    const z = @ceil(y);
+    comptime expectEqual(x, z);
+}
+
+fn testCeil(comptime T: type, x: T) void {
+    const y = x - 0.8;
+    const z = @ceil(y);
+    expectEqual(x, z);
+}
+
+test "@trunc" {
+    // FIXME: Generates a truncl function call
+    //testTrunc(f128, 12.0);
+    comptime testTrunc(f128, 12.0);
+    testTrunc(f64, 12.0);
+    comptime testTrunc(f64, 12.0);
+    testTrunc(f32, 12.0);
+    comptime testTrunc(f32, 12.0);
+    testTrunc(f16, 12.0);
+    comptime testTrunc(f16, 12.0);
+
+    const x = 14.0;
+    const y = x + 0.7;
+    const z = @trunc(y);
+    comptime expectEqual(x, z);
+}
+
+fn testTrunc(comptime T: type, x: T) void {
+    {
+        const y = x + 0.8;
+        const z = @trunc(y);
+        expectEqual(x, z);
+    }
+
+    {
+        const y = -x - 0.8;
+        const z = @trunc(y);
+        expectEqual(-x, z);
+    }
+}
+
+test "@round" {
+    // FIXME: Generates a roundl function call
+    //testRound(f128, 12.0);
+    comptime testRound(f128, 12.0);
+    testRound(f64, 12.0);
+    comptime testRound(f64, 12.0);
+    testRound(f32, 12.0);
+    comptime testRound(f32, 12.0);
+    testRound(f16, 12.0);
+    comptime testRound(f16, 12.0);
+
+    const x = 14.0;
+    const y = x + 0.4;
+    const z = @round(y);
+    comptime expectEqual(x, z);
+}
+
+fn testRound(comptime T: type, x: T) void {
+    const y = x - 0.5;
+    const z = @round(y);
+    expectEqual(x, z);
+}
+
 test "comptime_int param and return" {
     const a = comptimeAdd(35361831660712422535336160538497375248, 101752735581729509668353361206450473702);
     expect(a == 137114567242441932203689521744947848950);